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Algebraic Chess Notation

GerdIsenberg — Mon, 25 Sep 2017 21:28:07 GMT

Home * Chess * Game * Algebraic Chess Notation

Algebraic Chess Notation is a chess notation to record and represent moves of a human readable game notation. It is based on a system developed by Philipp Stamma to notate the target square by algebraic coordinates, and various forms to represent the origin square of the move, either by language dependent piece initials and/or file, rank- or square notation of the from- or origin square. Promotions must be disambiguated by including the promoted piece type, and castling usually has their own symbol strings ('O-O', 'O-O-O'). Some format variations also specify a captured piece, if any, for the purpose to make the notation reversible, and to go backward as easy as forward while re-playing a game.

Chess programs need to convert the list of encoded moves into a sequence of printable strings, or to render them inside a notation window. The move number of the game, starting by '1.' from the initial position, is prefix of the white halfmove, followed by a the black reply, often in a second column of a grid view. If a move notation starts with Black, also after embedded comments or annotations, a trailing ellipsis is used instead of a single dot.

<move> ::= <move number><move descriptor>
<move number> ::= <digit>[<digit>...]{'.' | '...'}

Modern chess programs, and their graphical user interface often support various modes to represent all kinds of game and move notations. Regarding input of moves from a user interface, or reading moves from text files, programs needs to parse strings accordantly.

Pure coordinate notation

Considering the common From-To move encoding inside a chess program, pure coordinate notation is a straight-forward chess notation to use only algebraic From- and To-coordinates. This notation omits any machine redundant piece letters for the moving and/or capturing pieces, and only has to specify the promoted piece as trailing letter in case of promotions.

<move descriptor> ::= <from square><to square>[<promoted to>]
<square>        ::= <file letter><rank number>
<file letter>   ::= 'a'|'b'|'c'|'d'|'e'|'f'|'g'|'h'
<rank number>   ::= '1'|'2'|'3'|'4'|'5'|'6'|'7'|'8'
<promoted to>   ::= 'q'|'r'|'b'|'n'

Pure algebraic coordinate notation was often used in early microcomputer chess programs, sometimes even with capital file letters. Some programs used a hyphen or 'x' delimiter between the coordinate substrings to distinguish quiet moves from captures in move outputs. While not common in human chess notation, pure coordinate notation has the advantage to avoid any ambiguity and is further easy convertible from a move list without the need of retrieving information from internal board representations, (i.e. which pieces occupy which squares). Even castling was often written as E1G1 or E1C1 instead of 'O-O' or 'O-O-O'.

XBoard

Per default, the Chess Engine Communication Protocol requires pure algebraic coordinate notation without from-to delimiters as input and output move format ^[1] .

UCI

The UCI communication protocol requires pure algebraic coordinate notation without from-to delimiters as well. Inside its specification the UCI move format is called "long algebraic notation" ^[2] , which might be considered slightly incorrect concerning leading piece character and dash or hyphen between from- and to coordinates, see LAN definition below.

Output Samples


8080 Chess Display ^[3]		Kempelen move list ^[4]

ICCF numeric notation

The language independent ICCF numeric notation as used in Correspondence chess is a numerical pure coordinate notation, giving coordinates by two digits (File '1'-'8) rather than letters ('a'-'h') for the file. In case of promotions a fifth trailing digit is used: '1' for queen, '2' for rook, '3' for bishop and '4' for knight.

Smith notation

The Smith notation designed by Warren D. Smith ^[5] , as used in the Internet Chess Club chess server, encodes moves with from-square, to-square, and to make it reversible, so it is as easy to go backwards in a game as forwards, what piece was captured, if any:

<Smith move descriptor> ::= <from square><to square>[<capture indicator>][<promoted to>]
<capture indicator> ::=  'P' | 'N' | 'B' | 'R' | 'Q'

Long Algebraic Notation (LAN)

Beside the already sufficient and unambiguous pure origin- and target-coordinates, LAN uses a leading redundant, national dependent uppercase piece letter or figurine piece symbol of the moving piece usually other than a pawn, to represent the move, which makes it more human readable and compatible with SAN and desciptive notation. However, for chess programs using pure from-to move encoding, converting the move list to LAN already requires a board representation in sync with the leading moves already played, to lookup the piece on the board.

<LAN move descriptor piece moves> ::= <Piece symbol><from square>['-'|'x']<to square>
<LAN move descriptor pawn moves>  ::= <from square>['-'|'x']<to square>[<promoted to>]
<Piece symbol> ::= 'N' | 'B' | 'R' | 'Q' | 'K'

English symbols Knight, Bishop, Rook, Queen and King.

Aart Bik's Chess for Android, G1 version with LAN representation ^[6]

Standard Algebraic Notation (SAN)

Standard algebraic notation (SAN) is the official notation of the FIDE which must be used in all recognized international competition involving human players ^[7] . Concerning computer chess, SAN is a representation standard for chess moves inside the Portable Game Notation standard using the ASCII Latin alphabet ^[8], and should be supported as default notation by all modern chess programs and their user interfaces ^[9].

Aart Bik's Chess for Android, latest version in SAN mode ^[10]

While otherwise similar to LAN, SAN suppresses redundant information concerning the from-square, while keeping the descriptive letter or symbol of pieces other than a pawn. SAN further suppresses the from-to hyphen, and in some variations also the capture indicator 'x' (or ':').

<SAN move descriptor piece moves>   ::= <Piece symbol>[<from file>|<from rank>|<from square>]['x']<to square>
<SAN move descriptor pawn captures> ::= <from file>[<from rank>] 'x' <to square>[<promoted to>]
<SAN move descriptor pawn push>     ::= <to square>[<promoted to>]

Ambiguities

If the piece is sufficient to unambiguously determine the origin square, the whole from square is omitted. Otherwise, if two (or more) pieces of the same kind can move to the same square, the piece's initial is followed by (in descending order of preference)

file of departure if different
rank of departure if the files are the same but the ranks differ
the complete origin square coordinate otherwise

Captures

Captures are denoted by the lower case letter "x" immediately prior to the destination square. Pawn captures with the omitted piece symbol, include the file letter of the originating square of the capturing pawn prior to the "x" character, even if not required for unambiguousness. Some SAN variations in printed media even omit the target rank if unambiguous, like dxe, which might not be accepted as input format.

En passant

The PGN-Standard does not require En passant captures have any special notation, and is written as if the captured pawn were on the capturing pawn's destination square.FIDE states the redundant move suffix "e.p." optional (after 1 July 2014) ^[11].

In the case of an ‘en passant’ capture, ‘e.p.’ may be appended to the notation.

Pawn promotion

A pawn promotion requires the information about the chosen piece, appended as trailing Piece letter behind the target square. The SAN PGN-Standard requires an equal sign ('=') immediately following the destination square.

Castling

Castling is indicated by the special notations, "O-O" for kingside castling and "O-O-O" for queenside castling. While the FIDE handbook ^[12] uses the digit zero, the SAN PGN-Standard requires the capital letter 'O' for its export format.

Converting Moves

Due to the most compact representation, considering ambiguities concerning the origin square, converting moves with pure from- and to-squares to SAN requires not only an underlying board representation to determine piece initials, but also legal move generation for a subset of moves to the destination square. Pseudo legal, but illegal moves for instance with a Pinned piece must not be considered in ambiguous issues in an export format.

XBoard 2

With the Chess Engine Communication Protocol version 2, one can use the feature command to select SAN as move format for both input and output ^[13] .

Figurine Algebraic Notation (FAN)

Figurine notation uses miniature piece icons instead of single letter piece abbreviations. This enables the moves to be read independent of the language. The Unicode Miscellaneous Symbols set includes all of the symbols necessary for FAN if appropriate fonts were installed on the computer ^[14] . Chess GUIs may alternatively use Scalable Vector Graphics or other scalable 2D Vector Graphics to render the symbols inside their views.

Vector Graphics

IsiChess, notation window with figurine LAN, using 2D Vector Graphics, see sample code

LaTeX

FAN in LaTeX ^[15]

Reading Chess

In an attempt of Computer vision, Henry S. Baird and Ken Thompson used optical character recognition along with various heuristics and applying the rules of chess, to "read" the figurine notation from Informant's Encyclopaedia of Chess Openings with high accuracy and a success rate of 99.995% on approximately one million characters (2850 games, 945 pages) ^[16] .

Publications

Henry S. Baird, Ken Thompson (1990). Reading Chess. IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 12, No. 6, pdf
Michel Goossens, Frank Mittelbach, Sebastian Rahtz, Denis Roegel, Herbert Voß (2007). The LATEXGraphics Companion. Second Edition, Addison-Wesley, ISBN-13: 978-0-321-50892-8, sample pdf, 10.1 Chess, 10.2 Xiangqi—Chinese Chess ^[17]

Forum Posts

correct SAN notation ? by Andreas Herrmann, CCC, December 19, 2002
Crafty (under winboard) question by Andrei Fortuna, CCC, December 21, 2003 » WinBoard
SAN Move Disambiguation -- looking for test positition by humble programmer, CCC, April 12, 2010 » PGN
Unicode values for chessmen by Steven Edwards, CCC, March 07, 2011
Determining From squares by David Whitten, CCC, December 04, 2011
What world have I been in - castling notation? by Lonnie Cook, CCC, September 13, 2014
SAN test position by Matthew Lai, CCC, September 11, 2016 » SAN
WAC using coordinate notation? by Erin Dame, CCC, September 17, 2017 » Pure coordinate notation, Win at Chess

External Links

Algebraic chess notation from Wikipedia
Desciptive notation from Wikipedia
Punctuation (chess) from Wikipedia
Chess symbols in Unicode from Wikipedia
Standard: Portable Game Notation Specification and Implementation Guide by Steven Edwards - 8.2.3: Movetext SAN (Standard Algebraic Notation)
SAN Kit: Implemented Standards for Chess Move Notation by Steven Edwards
FIDE handbook, Laws of Chess - Appendix C. Algebraic notation

References

^ Chess Engine Communication Protocol: 8. Commands from xboard to the engine
^ The UCI Specification
^ Processor Technology 8080 CHESS User's Manual. pdf, pdf
^ Kempelen Chess from Sierra Online from The Spacious Mind
^ Smith notation
^ Aart's Android Page
^ FIDE handbook, Laws of Chess - Appendix C. Algebraic notation
^ Standard: Portable Game Notation Specification and Implementation Guide by Steven Edwards - 8.2.3: Movetext SAN (Standard Algebraic Notation)
^ SAN Kit: Implemented Standards for Chess Move Notation by Steven Edwards
^ Aart's Android Page
^ FIDE handbook, Laws of Chess - Appendix C. Algebraic notation, C-9
^ FIDE handbook, Laws of Chess - Appendix C. Algebraic notation - C.13 Abbreviations
^ Chess Engine Communication Protocol: 9. Commands from the engine to xboard
^ Unicode values for chessmen by Steven Edwards, CCC, March 07, 2011
^ Michel Goossens, Frank Mittelbach, Sebastian Rahtz, Denis Roegel, Herbert Voß (2007). The LATEXGraphics Companion. Second Edition, Addison-Wesley, ISBN-13: 978-0-321-50892-8, sample pdf, 10.1 Chess, 10.2 Xiangqi—Chinese Chess
^ Henry S. Baird, Ken Thompson (1990). Reading Chess. IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 12, No. 6, pdf
^ LaTeX from Wikipedia

What links here?

Page	Date Edited
2D Graphics Board	Sep 23, 2017
Acornsoft Chess	Dec 11, 2016
Algebraic Chess Notation	Sep 25, 2017
Andreas Herrmann	Nov 7, 2014
Andrei Fortuna	Mar 6, 2014
Arena	Mar 16, 2018
Atom Chess	Dec 11, 2016
Captures	Oct 1, 2017
Castling	May 5, 2017
CHEKMO-II	Jan 3, 2018
Cheops (Miller)	Jan 13, 2017
Chess Game	Mar 28, 2017
CPW-Engine_algebraic	May 15, 2011
Dictionary	Aug 24, 2017
En passant	Jan 16, 2018
Encoding Moves	Mar 27, 2016
Entering Moves	Sep 7, 2017
Extended Position Description	Dec 2, 2017
Forsyth-Edwards Notation	Sep 10, 2017
Game Notation	Jan 11, 2018
Graphics Programming	Dec 22, 2017
GUI	Mar 16, 2018
HAL	Jun 14, 2016
Jester US	Sep 15, 2017
Ken Thompson	Sep 8, 2017
Mathematician	Apr 9, 2018
Matthew Lai	Dec 6, 2017
Megachess	Aug 1, 2016
Moves	Feb 19, 2018
Myopic	Nov 11, 2016
Origin Square	Oct 10, 2016
Piece Recognition	Sep 8, 2017
Portable Game Notation	Jan 11, 2018
Promotions	Jun 6, 2017
python-chess	Nov 4, 2017
SolusChess	Apr 21, 2015
Squares	Feb 15, 2015
Test-Positions	Feb 25, 2018
User Interface	Feb 21, 2018
Warren D. Smith	Sep 12, 2015
Win at Chess	Sep 25, 2017

Up one Level

Captures

GerdIsenberg — Sun, 01 Oct 2017 08:08:41 GMT

Home * Chess * Moves * Captures

Captures are tactical moves changing material balance where an opponent piece is removed from the board as part of the completion of the move. This is either done by moving a piece to a square, which is occupied by the opponent captured piece - or as a special case of pawn takes pawn, en passant.

Winning captures are those with least valuable aggressor of most valuable victim, where even a recapture would win material, and captures of pieces en prise, that is the union of undefended (hanging) pieces, as well as pieces defended inadequately. A static exchange evaluation might be applied to determine a victim is en prise or not. Equal captures are exchanges of equal valued pieces. Winning, as well as equal captures are subject of quiescence search. Some programs extend captures or recaptures under certain conditions, i.e. material becomes close to the root score again.

Capture Generation

With mailbox like square centric board representations, capture generation requires a so called blocker loop, while bitboards rely on attack generation and intersection with the set of opponent pieces.

Six times Take Five

capture	best case	worst case
capturing with the pawn
pxQ	winning queen	pawn for queen
pxR	winning rook	pawn for rook
pxB	winning bishop	pawn for bishop
pxN	winning knight	pawn for knight
pxP	winning pawn	exchanging pawns
capturing with the knight
nxQ	winning queen	knight for queen
nxR	winning rook	winning the exchange
nxB	winning bishop	exchanging minors
nxN	winning knight	exchanging minors
nxP	winning pawn	losing knight for pawn
capturing with the bishop
bxQ	winning queen	bishop for queen
bxR	winning rook	winning the exchange
bxB	winning bishop	exchanging minors
bxN	winning knight	exchanging minors
bxP	winning pawn	losing bishop for pawn
capturing with the rook
rxQ	winning queen	rook for queen
rxR	winning rook	exchanging rooks
rxB	winning bishop	losing exchange
rxN	winning knight	losing exchange
rxP	winning pawn	losing rook for pawn
capturing with the queen
qxQ	winning queen	exchanging queens
qxR	winning rook	losing queen for rook
qxB	winning bishop	losing queen for bishop
qxN	winning knight	losing queen for knight
qxP	winning pawn	losing queen for pawn
capturing with the king, always winning captures
kxQ	winning queen
kxR	winning rook
kxB	winning bishop
kxN	winning knight
kxP	winning pawn

Forum Posts

a question about the definition of winning capture in Rebel(diagrams) by Uri Blass, CCC, January 05, 2003
Reducing/Pruning Bad Captures (SEE < 0) by Edsel Apostol, CCC, August 19, 2011 » Pruning, Reductions, SEE
Sorting Captures by David Cimbalista, CCC, August 03, 2016 » Move Ordering
Ordering Capture Moves by Jason Fernandez, CCC, September 06, 2017 » Move Ordering - Captures

External Links

Capture (disambiguation) from Wikipedia
Al Jarreau - Take Five, live in Ohne Filter, SWR TV, Baden-Baden, Germany, 1994, YouTube Video
feat. Larry Williams, Neil Larsen, Charles “Icarus” Johnson, Andrew Ford, Steve Gadd

What links here?

Page	Date Edited
More Links
Algebraic Chess Notation	Sep 25, 2017
Amundsen	Sep 3, 2013
Amyan	Dec 10, 2013
Andscacs	Jan 16, 2018
Atlas	Nov 5, 2017
Atomic Chess	Nov 26, 2016
Battle Chess	Dec 12, 2016
Belle	Jan 18, 2018
Belzebub	Oct 20, 2015
Bitfoot	Sep 8, 2015
Blockage Detection	Oct 19, 2017
Bobby	Jan 7, 2016
Bobcat	Jun 27, 2017
BootChess	May 16, 2017
Brainless	Jun 24, 2017
Breakthrough (Game)	Aug 11, 2017
BremboCE	Feb 17, 2013
Capture Extensions	Oct 26, 2012
Captures	Oct 1, 2017
Castling rights	Jan 7, 2017
CHEOPS	Apr 18, 2015
Chess 0.5	Nov 20, 2016
Chess Champion Mark V	Sep 7, 2017
Chessmaps Heuristic	Aug 27, 2015
Chezzz	Jan 20, 2013
Crafty	Jan 28, 2018
Crazyhouse	Dec 27, 2017
CXG Sphinx	Jun 23, 2017
Cyrus 68K	Jan 7, 2016
DanaSah	Oct 9, 2017
David J. Wu	Jan 28, 2016
DayDreamer	Aug 22, 2016
Death Chess 5000	Apr 5, 2013
Delta Pruning	Dec 2, 2014
Diablo	May 17, 2016
Dispersion and Distortion	Nov 11, 2017
Dragon FR	Sep 9, 2016
Duck	Dec 12, 2016
Edsel Apostol	Nov 2, 2016
Efficient Generation of Sliding Piece Attacks	Nov 5, 2016
En passant	Jan 16, 2018
En prise	Oct 11, 2016
Encoding Moves	Mar 27, 2016
Entering Moves	Sep 7, 2017
ESC	Aug 14, 2013
Faile	May 27, 2014
Fidelity	Jan 7, 2016
Fifty-move Rule	Aug 9, 2017
Fixafan	Oct 2, 2015
Freccia	Dec 26, 2017
Freyr	Mar 6, 2014
Futility Pruning	Aug 30, 2017
General Setwise Operations	Feb 25, 2018
Genie	Feb 7, 2016
Golch	Dec 7, 2017
HAL	Jun 14, 2016
Halfmove Clock	Aug 9, 2017
Hanging Piece	Jan 14, 2017
Hannibal	Oct 4, 2017
HaQiKi D	Jul 26, 2017
Incremental Updates	Sep 6, 2017
Influence Quantity of Pieces	Jul 21, 2017
Irreversible Moves	Jan 25, 2014
JikChess	Nov 29, 2015
Joker IT	Sep 16, 2017
Kaissa	Apr 9, 2018
Killer Heuristic	Sep 14, 2017
Killer Move	Feb 16, 2017
Lachex	Jan 7, 2016
Laser	Dec 27, 2017
Last Best Reply	Jul 6, 2013
Late Move Reductions	Sep 25, 2017
Linked List	Oct 11, 2016
Master	Dec 28, 2017
Mater	Apr 26, 2016
Material Hash Table	Apr 3, 2014
Material Tables	May 5, 2017
Maverick	Jan 7, 2016
MessChess	Mar 6, 2014
Middlegame	Sep 6, 2016
MLChess	Jan 17, 2017
Move Generation	Jan 29, 2018
Move List	Jul 19, 2017
Move Ordering	Feb 27, 2018
Moves	Feb 19, 2018
Murka	Nov 11, 2016
MVV-LVA	Oct 26, 2017
MyChess	Dec 25, 2017
Null Move Pruning	Dec 2, 2017
Nullmover	Jul 21, 2013
Paladin	Jan 29, 2017
Papa	Jan 11, 2018
Passed Pawn Extensions	May 11, 2015
Pawn Levers (Bitboards)	Nov 11, 2017
PawnKing	Sep 5, 2014
Peasant	May 21, 2015
Pepito	Nov 27, 2014
Perft Results	Feb 10, 2018
Pharaon	Sep 2, 2017
Piece Drop	Feb 20, 2018
Piece-Lists	Feb 13, 2017
Pieces	Feb 19, 2018
Pieces versus Directions	Oct 6, 2016
Point Value by Regression Analysis	Aug 26, 2017
ProChess IT	Sep 30, 2015
Promotions	Jun 6, 2017
Prophet	Sep 30, 2017
Protector	Oct 12, 2017
Protej	Jul 27, 2014
Pruning	Jan 1, 2018
Pseudo-Legal Move	May 23, 2015
Querg	Dec 11, 2013
Quiescence Search	Aug 19, 2017
Quiet Moves	Mar 4, 2010
Rajah	Sep 12, 2012
Ralph Betza	Mar 12, 2014
Rebel	Feb 25, 2018
RedQueen	Nov 13, 2017
Repetitions	Jan 16, 2018
Reversible Moves	Mar 13, 2010
Rule of the Square	Sep 6, 2014
Search Statistics	Jan 16, 2018
SEE - The Swap Algorithm	Jun 5, 2017
Sensor Chess	Jun 7, 2013
SEX Algorithm	Nov 25, 2014
Sjaak (Glebbeek)	Oct 4, 2017
Skewer	Oct 22, 2014
Sliding Piece Attacks	May 27, 2016
Sliding Pieces	Aug 3, 2017
Smash	May 11, 2016
Spike	Jan 7, 2016
Static Exchange Evaluation	Dec 14, 2017
Strategic Test Suite	Dec 19, 2016
Sungorus	Apr 11, 2014
Syzygy Bases	Apr 19, 2018
Table-driven Move Generation	Feb 19, 2017
Tactical Moves	Sep 22, 2010
Tao	Jan 8, 2016
Target Square	Oct 26, 2017
The King	Jan 21, 2018

Up one Level

Castling

GerdIsenberg — Fri, 05 May 2017 10:03:51 GMT

Home * Chess * Moves * Castling

		Castling is a composite move of King and Rook at the same time. In standard chess it consists of moving a king two squares towards the rook and executing a jump of a rook over the king.
Marina Kalinovsky, Castling, 1961 ^[1]

Rules

The prequisites for doing it are as follows:

the king and the relevant rook must not be moved, considered as castling rights inside a chess position
the king must not be in check
no square between king's start and final square may be controlled by the enemy

Chess960

In Chess960 castling is a move reaching the position just like after standard chess castling, which may be achieved by (a) moving the king to c1 or g1 ant then executing a jump by relevant rook (b) jumping with the rook over a king already placed on c1 or g1 (c) interchanging the positions of king and rook ^[2].

Shogi

A formation achieved after castling is called a castle. This is often contrasted with a castle in the game of Shogi, requiring several moves to complete, but it seems wrong, since chess also has several standard defensive castle formations - like the one after fianchetto of a king's bishop or the one with a knight on g7, often achieved in the Old Benoni. For that reason it might be interesting to use shogi programming concepts of a castle map and an attack map in chess.

Forum Posts

1982

Re: bug in chess program by Bruce C. Wright @ Duke University, net.chess, December 2, 1982
Re: Origin of Castling by Bruce C. Wright @ Duke University, net.chess, December 4, 1982

2000 ...

Castling legality check by mjlef, Winboard Forum, January 04, 2007
Saving castling states and en passant history by Eric Lang, CCC, November 27, 2008 » En passant
0x88 FRC castle questions by Daniel Uranga, Winboard Forum, December 12, 2009 » Chess960

2010 ...

Castling legality check by Stef Luijten, CCC, May 03, 2011
Castling long by Lyudmil Tsvetkov, CCC, August 05, 2013
Castling: A counter-intuitive result by Steven Edwards, CCC, September 03, 2013
Abundance of castling vs en passant rights by Kirill Kryukov, CCC, April 14, 2014 » En passant
Castling Evaluation by Dennis Sceviour, CCC, August 02, 2016 » King Safety

External Links

Castling from Wikipedia
Artificial castling from Wikipedia

References

^ Tableaux Échecs - Chess Paintings
^ 0x88 FRC castle questions by Daniel Uranga, Winboard Forum, December 12, 2009

What links here?

Page	Date Edited
1K ZX Chess	Oct 1, 2015
Acornsoft Chess	Dec 11, 2016
Algebraic Chess Notation	Sep 25, 2017
Atlas	Nov 5, 2017
Atom Chess	Dec 11, 2016
BootChess	May 16, 2017
Brainstorm	Jun 24, 2017
Castling	May 5, 2017
Castling rights	Jan 7, 2017
Charly	Jan 10, 2013
CHEKMO-II	Jan 3, 2018
Chess Position	Sep 10, 2017
Chess960	Sep 27, 2016
ChessLin	May 17, 2017
Color Flipping	May 17, 2017
David Forthoffer	Apr 25, 2016
Dennis Sceviour	Feb 14, 2018
Development	Jan 17, 2018
Diagonal Mirroring	Jun 29, 2013
Dictionary	Aug 24, 2017
DirGolem	Jun 5, 2016
Djinn	Feb 8, 2016
EGA Chess	Nov 30, 2017
En passant	Jan 16, 2018
Encoding Moves	Mar 27, 2016
Ethereal	Mar 20, 2018
Evaluation Overlap	Jul 19, 2016
Evert Glebbeek	Sep 25, 2017
Exacto	Oct 3, 2015
Fianchetto	Feb 18, 2015
Firstchess	Nov 27, 2014
General Setwise Operations	Feb 25, 2018
Genie	Feb 7, 2016
Getting Started	Jan 20, 2014
Halfmove Clock	Aug 9, 2017
iota	Feb 10, 2016
Irreversible Moves	Jan 25, 2014
Jonathan Warkentin	Jun 29, 2014
Kaissa	Apr 9, 2018
King	Feb 26, 2013
King Safety	Feb 14, 2018
Kirill Kryukov	Apr 16, 2014
Lachex	Jan 7, 2016
Lancaster	Aug 30, 2016
Lars Rasmussen	Apr 25, 2016
LarsenVB	Jun 24, 2017
Legal Move	Feb 16, 2017
Little Rook Chess	Sep 1, 2015
Losing Chess	Sep 18, 2017
Lyudmil Tsvetkov	Mar 28, 2018
MANIAC I	Nov 17, 2016
Mark Lefler	Nov 23, 2017
Mark Taylor	Jan 7, 2016
Mate-in-two	Oct 14, 2016
Middlegame	Sep 6, 2016
Mini Chess	Jun 7, 2013
Moves	Feb 19, 2018
MyChess	Dec 25, 2017
Novag Micro Chess	Jan 16, 2013
Opening	Jun 25, 2017
Ostrich	Dec 28, 2017
Pin	Mar 7, 2017
Pseudo-Legal Move	May 23, 2015
Quad-Bitboards	Jan 30, 2017
Quiet Moves	Mar 4, 2010
Reversible Moves	Mar 13, 2010
Robocide	May 11, 2016
Shatranj	Jul 26, 2017
Sito Dekker	Apr 25, 2016
SOMA	Mar 25, 2015
Square Attacked By	Jan 20, 2018
Stef Luijten	Apr 26, 2015
Tempo	Jan 17, 2018
The A.R.B Chess System	May 24, 2016
Toledo	Sep 23, 2017
Turochamp	Dec 14, 2017
Vertical Flipping	Oct 10, 2013
Vice	Mar 8, 2016
William Chase	Jan 21, 2016
Z-Chess	Dec 23, 2017

Up one Level

Castling rights

GerdIsenberg — Sat, 07 Jan 2017 10:29:13 GMT

Home * Chess * Position * Castling rights

The Castling rights specify whether both sides are principally able to castle king- or queen side, now or later during the game - whether the involved pieces have already moved or in case of the rooks, were captured. Castling rights do not specify, whether castling is actually possible, but a pre-condition for both wing castlings.

Two bits per side are appropriate to store the castling rights, often one uses one nibble to store the rights for both sides inside a position object, a kind a array of four booleans. In make move one has to consider that king-moves reset both castling bits per side.

Rook-moves from their original square, or captures of rooks on their original squares reset the appropriate castling bits per wing and side. Changed castling rights should be considered in the zobrist key of the position, to reflect the irreversibility of the otherwise reversible move, concerning repetitions. On the other hand, changed castling rights don't necessarily reset the halfmove clock regarding the fifty-move rule.

Forum Posts

Saving castling states and en passant history by Eric Lang, CCC, November 27, 2008 » En passant
0x88 FRC castle questions by Daniel Uranga, Winboard Forum, December 12, 2009 » Chess960
Updating castling rights by Jan Brouwer, CCC, March 19, 2010
ep and castle rights hashing by Natale Galioto, CCC, September 15, 2013 » En passant, Repetitions, Transposition Table
3rd repetition, a case where not cause castle rights... but by Luis Babboni, CCC, April 14, 2016 » Repetitions
Enpass + Castling for Zorbist hashes by Andrew Grant, CCC, January 06, 2017 » En passant, Zobrist Hashing

External Links

What links here?

Page	Date Edited
AlphaZero	Feb 10, 2018
Andrew Grant	Jan 13, 2018
BigLion	Sep 28, 2016
Board Representation	Dec 11, 2017
Castling	May 5, 2017
Castling rights	Jan 7, 2017
Chess Position	Sep 10, 2017
Coiled	Mar 12, 2017
Color Flipping	May 17, 2017
Copy-Make	May 23, 2017
CTG	Aug 22, 2016
Dabbaba	Oct 21, 2014
Deep Pink	Feb 6, 2017
Dictionary	Aug 24, 2017
Donna	Aug 17, 2017
En passant	Jan 16, 2018
Eval Tuning in Deep Thought	Jun 7, 2016
Evaluation of Pieces	Jan 8, 2018
Extended Position Description	Dec 2, 2017
Forsyth-Edwards Notation	Sep 10, 2017
Gibbon	Dec 23, 2014
Gk	Oct 9, 2017
Halfmove Clock	Aug 9, 2017
Horizontal Mirroring	Jun 29, 2013
Incremental Updates	Sep 6, 2017
Irreversible Moves	Jan 25, 2014
Kaissa	Apr 9, 2018
King Safety	Feb 14, 2018
Make Move	Mar 2, 2016
Mini Chess	Jun 7, 2013
Murka	Nov 11, 2016
Paladin	Jan 29, 2017
Pseudo-Legal Move	May 23, 2015
Repetitions	Jan 16, 2018
Reversible Moves	Mar 13, 2010
Shield	May 17, 2017
Sloppy	Sep 17, 2016
Transposition Table	Apr 19, 2018
Unmake Move	Jun 10, 2017
Zobrist Hashing	Jan 22, 2018

Up one Level

Check

GerdIsenberg — Thu, 01 Feb 2018 19:43:04 GMT

Home * Chess * Check

		Inside a game of chess, a check occurs if a king is under immediate attack by one (or two) opponent pieces. If the king has no way to remove it from attack on the next move, the check is even checkmate. Since check is crucial concerning the outcome of game and the horizon effect, check extensions might be applied to evade the check.
Samuel Bak - Lighthouse ^[1]

Kind of Checks

Single Check

The king is attacked by one opponent piece, either by the piece which just moved directly attacking the king, or alternatively a discovered check where a distant sliding piece attacks the king by opening the ray in opponent king direction with another piece.

Double Check

A double check occurs if the moving piece directly attacks the king but also discovers a distant sliding attacker.

In Check Detection

Whether the side to move is in check is essential to know inside the search for various reasons. It might be checkmate, and most pseudo-legal moves generated may be illegal, leaving the king attacked. Null move would yield in an illegal position as well, at or below the horizon we don't want to stand pat if material balance or static evaluation is far greater than beta.

By last Move

The cheapest and most straightforward way to detect checks is to consider the previous move just made by the opponent. It might be a direct check or discovered check, so one has to test whether piece on target square attacks the king, or whether piece on origin square is attacked by an own sliding piece on an otherwise open ray in opponent king direction ^[2]. If the last move was an en passant capture, one has to consider a few more complicated cases of possible discovered checks, since the captured pawn is not on the target square, and two pawns disappear from the 4th (5th) rank.

Attack Tables

Based on the design and data structure of a chess program, an incremental updated attack and defend map may immedeatly answer whether the king is under attack of one or even two opponent pieces.

On the Fly

With bitboards one may determine a square attacked as mentioned in checks and pinned pieces.

Getting out of check

While in check, it is recommended to perform a specialized Move Generation for check evasion of either a reasonable subset of all pseudo-legal moves or even a strict legal move generation:

Double Check

Only king moves to non attacked squares, sliding check x-rays the king

Single Check

Capture of checking piece. The capturing piece is not absolutely pinned
King moves to non attacked squares, sliding check x-rays the king
Interposing moves in case of distant sliding check. The moving piece is not absolutely pinned.

Perpetual Check

A perpetual check occurs if one player forces an "endless" series of checks with repeated reversible moves, finally resulting in a draw by threefold repetitions.

Publications

Richard L. Smith, Fernand Gobet, Peter Lane (2009). Checking chess checks with chunks: A model of simple check detection. ICCM 2009 » CHREST, Chunking

Forum Posts

1997 ...

quiescence search by Andrew Tridgell, rgcc, April 16, 1997 » Quiescence Search, Crafty

2000 ...

Checks in the Qsearch by Scott Gasch, CCC, June 28, 2002 » Quiescence Search
Idea for check function by Zach Wegner, CCC, November 14, 2002
Fast check detection in bitboard engine by Jean-Francois Romang, CCC, December 10, 2003
Rebel's long checks concept in QS by milix, CCC, January 23, 2004 » Rebel, Quiescence Search
Qsearch Checks by Tor Lattimore, CCC, August 29, 2004 » Quiescence Search
Checks in QSearch by Dan Honeycutt, Winboard Programming Forum, November 23, 2004 » Checks in Quiescence Search

2005 ...

in check test by Anonymous , Winboard Forum, July 07, 2005
How to Best Limit Checks in the Quiescence ? by Stuart Cracraft, CCC, August 20, 2007 » Checks in Quiescence Search
discovered check definition by Uri Blass, CCC, September 12, 2007 » Discovered Check
checks in q-search by Robert Hyatt, CCC, September 02, 2008

2010 ...

Standpat and check by Vlad Stamate, CCC, February 06, 2010 » Standing Pat
Detecting Checks by beneficii, Winboard Programming Forum, November 27, 2010
out of check move ordering by Don Dailey, CCC, March 12, 2011 » Move Ordering
checks in quies by Larry Kaufman, CCC, March 22, 2012 » Quiescence Search
What is (in your opinion) the best check validation method? by goodgame0111, OpenChess Forum, February 24, 2014
Spite checks by Harm Geert Muller, CCC, May 13, 2014

2015 ...

Check-extension in QS by Harm Geert Muller, CCC, April 03, 2015 » Checks in Quiescence Search
Ostrich tactics and pointless checks by Colin Jenkins, CCC, May 29, 2015 » Horizon Effect
Checks in qsearch - must-have or optional? by Martin Fierz, CCC, March 15, 2016 » Checks in Quiescence Search
perpetual check position by Erin Dame, CCC, August 16, 2016
Spite checks, again by Harm Geert Muller, CCC, October 23, 2016

External Links

References

^ Chess in the Art of Samuel Bak, Center for Holocaust & Genocide Studies, University of Minnesota
^ Idea for check function by Zach Wegner, CCC, November 14, 2002

What links here?

Page	Date Edited
AI Chess	Jan 7, 2016
Anastasios Milikas	Nov 29, 2017
Andrew Tridgell	Aug 3, 2015
Anechka	Mar 20, 2014
Atomic Chess	Nov 26, 2016
BCP	Dec 30, 2015
Bebe	Dec 23, 2017
BELCT 2001	Apr 4, 2017
Blockade	Oct 19, 2017
Bobby	Jan 7, 2016
BootChess	May 16, 2017
BP	Jan 7, 2016
Carballo	Oct 2, 2016
Check	Feb 1, 2018
Check Extensions	Apr 19, 2018
Checkmate	Apr 13, 2018
Checks and Pinned Pieces (Bitboards)	Aug 14, 2013
Cheng	Jul 30, 2017
Chess	Jan 21, 2018
Chess Champion Mark V	Sep 7, 2017
Chess Game	Mar 28, 2017
Chess Wizard	Dec 22, 2014
chess22k	Apr 23, 2018
ChessBrainVB	Jun 24, 2017
Crafty	Jan 28, 2018
CXG Sphinx	Jun 23, 2017
Cyrus 68K	Jan 7, 2016
Dabbaba	Oct 21, 2014
Dan Honeycutt	Mar 13, 2014
Diablo	May 17, 2016
Dictionary	Aug 24, 2017
DirGolem	Jun 5, 2016
Discovered Check	Feb 1, 2018
Djinn	Feb 8, 2016
Double Attack	Oct 22, 2014
Double Check	Apr 4, 2013
Dragon FR	Sep 9, 2016
Draw	Apr 14, 2018
DrunkenMaster	Nov 1, 2016
Encoding Moves	Mar 27, 2016
Erin Dame	Dec 2, 2017
Eveann	Apr 3, 2017
FCP	Jun 15, 2013
Fidelity	Jan 7, 2016
Fortress	Feb 1, 2018
Futility Pruning	Aug 30, 2017
Genie	Feb 7, 2016
George Baylor	Sep 22, 2014
Ghost	Feb 2, 2018
Gibbon	Dec 23, 2014
HAL	Jun 14, 2016
Harm Geert Muller	Mar 31, 2018
Horizon Effect	Sep 10, 2017
Interference	May 20, 2011
Kaissa	Apr 9, 2018
King	Feb 26, 2013
Knowledge	Jul 22, 2017
Lachex	Jan 7, 2016
Larry Kaufman	Jan 28, 2018
Laser	Dec 27, 2017
Late Move Reductions	Sep 25, 2017
Legal Move	Feb 16, 2017
Losing Chess	Sep 18, 2017
Martin Fierz	Apr 26, 2018
Mate Search	Oct 22, 2016
Mater	Apr 26, 2016
Maverick	Jan 7, 2016
MessChess	Mar 6, 2014
Monarch	Nov 19, 2014
Move Generation	Jan 29, 2018
Move Ordering	Feb 27, 2018
Moves	Feb 19, 2018
Murka	Nov 11, 2016
One Reply Extensions	Dec 31, 2014
Overloading	May 5, 2017
Pawn Race	Dec 16, 2017
Pertti Saariluoma	Jun 13, 2017
Pin	Mar 7, 2017
Point Value	Mar 31, 2018
ProChess IT	Sep 30, 2015
Pseudo-Legal Move	May 23, 2015
python-chess	Nov 4, 2017
Querg	Dec 11, 2013
Quiescence Search	Aug 19, 2017
Quiet Moves	Mar 4, 2010
Rebel	Feb 25, 2018
Repetitions	Jan 16, 2018
Retrograde Analysis	Mar 21, 2017
RISC 2500	Jan 7, 2016
Scott Gasch	Nov 29, 2016
SCP	Jun 16, 2016
Search Explosion	Mar 30, 2017
SEE	Jan 14, 2013
SEX Algorithm	Nov 25, 2014
Skewer	Oct 22, 2014
Stalemate	Feb 21, 2018
Static Exchange Evaluation	Dec 14, 2017
Stuart Cracraft	May 19, 2017
SuperChess	Dec 7, 2016
Tactical Moves	Sep 22, 2010
Tactics	Jan 12, 2018
Tao	Jan 8, 2016
Test-Positions	Feb 25, 2018
Tor Lattimore	Jan 13, 2013
Turochamp	Dec 14, 2017
Undermining	Jun 10, 2012
Vlad Stamate	Dec 31, 2014
WildCat	Nov 11, 2016
Winter	Jan 23, 2018
Zappa	Oct 24, 2017
Zeus	Jan 3, 2018

Up one Level

Checkmate

GerdIsenberg — Fri, 13 Apr 2018 13:06:42 GMT

Home * Chess * Checkmate

		Checkmate (often shortened to mate) occurs if a king is under immediate attack by one (or two) opponent pieces (in check) and has no way to remove it from attack on the next move. Checkmate is the object of the game of chess, it ends with the mate giving player as the winner, and the mated player the loser.
Shannon Larratt - Fool's mate (2007) ^[1] ^[2] ^[3]

Mate Score

At the Root

At the root the score of a mated player is the worst score one can get, that is a negative score with the greatest absolute value of the score range. It is quite common and sufficient to use something like this in C, C++:

#include <limits.h>
/* (-32768/2 = -16384) */
#define VALUE_MATED (SHRT_MIN/2)

Inside a 16-bit short integer range, assuming centipawn evaluation, it translates to roughly being 16 queens down. Note that using SHRT_MIN instead of SHRT_MIN/2 as mate value has issues in greater/less comparisons of additive expressions, where summands around SHRT_MIN or SHRT_MAX may under- or overflow, which has somehow relaxed with the advent of the usual 32-bit sign-extension.

Down the Tree

Inside a negamax based search, most ^[4] programs assign VALUE_MATED + ply distance to the root as worst case score if entering a node, which if propagated as mate score along the Principal variation to the root, translates in mate in odd plies (positive values), or getting mated in even plies. However, those scores need ply-adjustment if stored as exact score inside the transposition table, and re-adjustment if retrieving from TT. An alternative approach, not only related to mate scores was proposed by Harm Geert Muller, The Delay Penalty as implemented in Micro-Max ^[5] ^[6] ^[7] ^[8].

Detecting Mate

Some programs rely on pseudo-legal move generation, and find Checkmate if all those moves are in fact illegal after making and finding the "refutation" of capturing the king. At the latest, if no legal move was found, programs need the information whether the king is in check to decide about checkmate or stalemate score. Despite, most programs (should be) are aware of check in advance, and use special move generator(s) if in check or even in double check:

Double check
- Only King moves or captures
Single check
1. Capture the checking piece
2. King moves or captures
3. In case of distant checks, interposing a piece between the threatening sliding piece and the king

Publications

1952

Dietrich Prinz (1952). Robot Chess. Research, Vol. 6, reprinted 1988 in Computer Chess Compendium » Mate-in-two

1965 ...

George W. Baylor (1965). Report on a Mating Combinations Program. SDC Paper, No. SP-2150, System Development Corporation, Santa Monica, Calif. » Mater
George W. Baylor, Herbert A. Simon (1966). A chess mating combinations program. AFIPS Joint Computer Conferences, reprinted in Herbert A. Simon (1979). Models of Thought. Yale University Press, pp. 181-200, in David Levy (ed.) (1988). Computer Chess Compendium.
George W. Baylor (1966). A Computer Model of Checkmating Behaviour in Chess. in Adriaan de Groot, Walter R. Reitman (eds.) (1966). Heuristic Processes in Thinking. International Congress of Psychology, Nauka, Moscow
Vladimir E. Alekseev (1969). Compilation of Chess Problems on a Computer. Technical translation FSTC-HT-23-124-69, US Army, NTIS AD 689470 (Problemy Kibernetiki, 19, 1967)

1980 ...

John Birmingham, Peter Kent (1980). Mate at a Glance. Advances in Computer Chess 2, reprinted in Computer Chess Compendium
Max Bramer (1982). Finding Checkmates. Computer & Video Games, Spring 1982, pdf hosted by Mike Watters » Mater
Don Beal (1984). Mating Sequences in the Quiescence Search. ICCA Journal, Vol. 7, No. 3

1990 ...

Thomas Mally (1993). Matt in Wieviel? PC Schach 3/93 (German)

2000 ...

Vladan Vučković (2004). Realization of the Chess Mate Solver Application. Yugoslav Journal of Operations Research, Volume 14, Number 2, pdf
Fridel Fainshtein (2006). An Orthodox k-Move Problem-Composer for Chess Directmates. M.Sc. thesis, Bar-Ilan University, pdf
Fridel Fainshtein, Yaakov HaCohen-Kerner (2006). A Chess Composer of Two-Move Mate Problems. ICGA Journal, Vol. 29, No. 1, pdf
Ami Hauptman, Moshe Sipper (2007). Evolution of an Efficient Search Algorithm for the Mate-In-N Problem in Chess. EuroGP 2007, pdf

2010 ...

Azlan Iqbal (2010). Aesthetics in Mate-In-3 Combinations. Part I Combinatorics and Weights, ICGA Journal, Vol. 33, No. 3
Azlan Iqbal (2010). Aesthetics in Mate-In-3 Combinations. Part II Normality, ICGA Journal, Vol. 33, No. 4
Taichi Ishitobi, Alessandro Cincotti, Hiroyuki Iida (2013). Shape-Keeping Technique and Its Application to Checkmate Problem Composition. 2013 AIIDE Workshop

Forum Posts

1997 ...

Mate in 4 explanation by Howard Exner, CCC, October 07, 1997
Mate in 30 testposition for Rebel 9! by Jouni Uski, CCC, November 20, 1997 » Rebel
Mate in 18 moves? by Ed Schröder, CCC, January 09, 1998
Using too-shallow mate scores from the hash table by David Eppstein, CCC, July 05, 1998
Re: Using too-shallow mate scores from the hash table by David Eppstein, CCC, July 06, 1998
Re: Using too-shallow mate scores from the hash table by Don Dailey, CCC, July 07, 1998
Solve for Mate by Trefor Deane, CCC, July 11, 1998
Mate the Royal Couple by Hans Havermann, CCC, November 14, 1998
Estimated # of checkmate positions? by Jeff Anderson, CCC, July 07, 1999
Mate solvers... by Dann Corbit, CCC, September 07, 1999
Interesting mate test for hashing by Robert Hyatt, CCC, September 10, 1999 » Transposition Table
Is "Interesting mate test..." the longest ever thread.... by Tina Long, CCC, September 11, 1999

2000 ...

Mate in 1 - but Fritz 6 needs 1 hour!!! by Christoph Fieberg, CCC, August 10, 2000
What's the fastest mate-finder? by Michel Langeveld, CCC, August 27, 2000
Questions about Mate Searching by William Bryant, CCC, September 23, 2000 » Mate Search
Mate in 7 moves - diagram by Eduard Nemeth, CCC, September 27, 2000 » Zugzwang
Static Mate Detection by Gerd Isenberg, CCC, January 22, 2002 » Mate at a Glance
First mate in 2, then mate in 3 by Albert Bertilsson, CCC, March 03, 2003
Easy mate by Frank Phillips, CCC, September 13, 2003 ^[9]

2005 ...

Shortest ever mate? by Tord Romstad, CCC, October 30, 2005
The Code for the Rybka-Mate-Bug by Chrilly Donninger, CCC, December 13, 2005 » Rybka
Unusual Mate in 3 by Charles Roberson, CCC, March 02, 2006
Delayed-loss-bonus discussion goes here by Harm Geert Muller, CCC, September 28, 2007
mate detetion issue by Mike Adams, CCC, October 24, 2008 » Connect Four, Fail-Soft
How to check for checkmate/stalemate programmatically? by Valentin, Rybka Forum, November 22, 2008 » Stalemate
Draw by repetition when mate is possible by Mathieu Pagé, CCC, December 30, 2008 » Repetitions

2010 ...

Puzzle with mate scores in TT by Robert Purves, CCC, December 10, 2010 » Score, Transposition Table
Yet Another Mate Solving Test by Jouni Uski, CCC, January 14, 2011
Mate score in TT by Marco Costalba, CCC, December 28, 2011 » Score, Transposition Table
Checkmate In Zero by Christopher Conkie, CCC, January 02, 2013
To be, or not to be checkmated by Harm Geert Muller, CCC, April 18, 2014
Mate score from the transposition table by Evert Glebbeek, CCC, October 25, 2014 » Score, Transposition Table

2015 ...

Remember Leonid Liberman (author of LLCHESS)? by Dann Corbit, CCC, May 23, 2015 » Leonid's Positions
TT Mate scores by rgoomes, OpenChess Forum, February 10, 2016 » Score, Transposition Table
Funny mate in 6 by Sergei S. Markoff, CCC, February 17, 2016
Mate scores from IID by Matthew R. Brades, CCC, August 16, 2016 » Internal Iterative Deepening
Why do engines lack mate solving? by Rasmus Althoff, CCC, October 15, 2016 » Mate Search
Mate scores in TT (a new?... approach) by Vince Sempronio, CCC, April 09, 2018
Yet another Mate scores in TT thread by Andrew Grant, CCC, April 12, 2018 » Score, Transposition Table

Leonid's Positions

Mate in ...? by Leonid, CCC, February 12, 2000
Two mate positions to solve by Leonid, CCC, September 02, 2000
Two mate position to solve by Leonid, CCC, September 06, 2000
What shortest mate that you can find for this position? by Leonid, CCC, January 17, 2001
If you like to find a mate... by Leonid, CCC, January 18, 2001
If you want solve one mate... by Leonid, CCC, January 21, 2001
One easy mate to solve... by Leonid, CCC, January 22, 2001
One average mate position... by Leonid, CCC, January 23, 2001
If you like to solve easy forced mate... by Leonid, CCC, January 24, 2001
If you like to solve average mate position... by Leonid, CCC, January 25, 2001
If you like to solve real mate... by Leonid, CCC, January 27, 2001
If you like to solve mate from real game... by Leonid, CCC, January 28, 2001
If you like forced mate... by Leonid, CCC, January 30, 2001
Forced mate position to solve... by Leonid, CCC, January 31, 2001
If you like to solve a mate... by Leonid, CCC, February 01, 2001
Forced mate so solve... by Leonid, CCC, February 05, 2001
If you like to solve easy mate... by Leonid, CCC, February 08, 2001
If you like to solve a mate... by Leonid, CCC, February 09, 2001
If you like to crush easy mate... by Leonid, CCC, February 10, 2001
If you like to solve mate for light position... by Leonid, CCC, February 11, 2001
If you like to solve mate... by Leonid, CCC, February 14, 2001
If you like solving forced mate... by Leonid, CCC, February 15, 2001
If you like to solve one easy mate... by Leonid, CCC, February 16, 2001
Easy mate to solve... by Leonid, CCC, March 04, 2001
If you like to sove a mate... by Leonid, CCC, March 10, 2001
If you are ready to solve one mate... by Leonid, CCC, April 11, 2001
If you like easy mate... by Leonid, CCC, April 12, 2001
If you want to solve one mate... by Leonid, CCC, April 14, 2001
If you enjoy like me solving mates... by Leonid, CCC, April 16, 2001
Mate that every program will solve... by Leonid, CCC, April 17, 2001
One mate to solve... by Leonid, CCC, April 22, 2001
Mate to solve... by Leonid, CCC, April 23, 2001
Mate that every program will find by Leonid, CCC, April 26, 2001
Mate to solve for champions... by Leonid, CCC, April 29, 2001
One mate to solve for fittest programs by Leonid, CCC, May 04, 2001
Very easy mate to solve by Leonid, CCC, May 05, 2001
One mate to solve... by Leonid, CCC, May 06, 2001
Mate to solve in two flavous by Leonid, CCC, May 07, 2001
One mate to solve... by Leonid, CCC, May 08, 2001
One mate to solve... by Leonid, CCC, May 15, 2001
One very easy mate to solve by Leonid, CCC, May 21, 2001
One mate to solve... by Leonid, CCC, May 30, 2001
One mate to solve... by Leonid, CCC, June 02, 2001
Mate to solve for good program by Leonid, CCC, June 07, 2001
One mate to solve for Champion! by Leonid, CCC, June 16, 2001
One mate to solve by Leonid, CCC, July 17, 2001
One mate to sove for Champions! by Leonid, CCC, September 02, 2001
One mate to solve for Champions! by Leonid, CCC, October 02, 2001
A mate for Leonid by Sven Reichard, CCC, October 10, 2001
Try this mate by Leonid, CCC, October 16, 2001
Try solve this mate by Leonid, CCC, October 21, 2001
Try this moderate mate by Leonid, CCC, October 27, 2001
One easy mate by Leonid, CCC, November 04, 2001
Very easy mate to solve by Leonid, CCC, December 22, 2001
Find a mate by Leonid, CCC, August 03, 2002
One mate in 10 to solve by Leonid, CCC, August 10, 2002
One mate in 11 by Leonid, CCC, September 07, 2002
Try to solve mate by Leonid, CCC, September 14, 2002
Mate slightly harder by Leonid, CCC, August 25, 2003
Mate that should be easy by Leonid, CCC, October 19, 2003
Heavy mate position but easy to solve by Leonid, CCC, October 20, 2003
Mate to torture by Leonid, CCC, November 02, 2003
Try very easy mate by Leonid, CCC, November 04, 2003
Try to solve very populated mate by Leonid, CCC, November 05, 2003
Very easy mate by Leonid, CCC, November 06, 2003

External Links

References

^ Shannon Larratt - Fool's mate (2007) from Tableaux ayant pour sujet les échecs
^ In Loving Memory of Shannon Larratt 1:24, YouTube Video
^ Shannon Larratt is Zentastic › Blog archives, February 09, 2007
^ The Code for the Rybka-Mate-Bug by Chrilly Donninger, CCC, December 13, 2005
^ Evaluation: Aging - The Delay Penalty from Micro-Max by Harm Geert Muller
^ Re: Transposition Tables by Harm Geert Muller, CCC, September 26, 2007
^ Delayed-loss-bonus discussion goes here by Harm Geert Muller, CCC, September 28, 2007
^ Seeing a promotion, but not playing it... by Harm Geert Muller, CCC, January 24, 2010
^ Frank Phillips' KNNKP position revisited ... by Guy Haworth, CCC, September 18, 2003 » Endgame Tablebases

What links here?

Page	Date Edited
ACM 1974	Jan 19, 2018
Albert Bertilsson	Jun 6, 2017
Alybadix	Apr 26, 2016
BCP	Dec 30, 2015
Bionic	May 27, 2013
Check	Feb 1, 2018
Checkmate	Apr 13, 2018
Chess	Jan 21, 2018
Chess Champion Super System III	Sep 17, 2015
Chess Game	Mar 28, 2017
Chess Problems, Compositions and Studies	Feb 19, 2018
Chest	Mar 3, 2015
Chinese Chess	Jan 16, 2018
Coko	Jul 13, 2015
Composer	Sep 3, 2017
Connect Four	Jan 31, 2018
CXG Sphinx	Jun 23, 2017
Cyrus 68K	Jan 7, 2016
Dabbaba	Oct 21, 2014
Dictionary	Aug 24, 2017
Dietrich Prinz	Oct 14, 2016
DirGolem	Jun 5, 2016
Draw	Apr 14, 2018
Edwards' Tablebases	Sep 26, 2016
Endgame Tablebases	Mar 6, 2018
Fail-Soft	Jun 2, 2017
Fidelity	Jan 7, 2016
Fifty-move Rule	Aug 9, 2017
Futility Pruning	Aug 30, 2017
Genie	Feb 7, 2016
George Baylor	Sep 22, 2014
Gibbon	Dec 23, 2014
Giraffe	Jan 8, 2018
Gustav	May 14, 2016
Harm Geert Muller	Mar 31, 2018
Houdini	Apr 14, 2018
Interception	May 21, 2011
Internal Iterative Deepening	Feb 5, 2018
Jouni Uski	Sep 28, 2017
Kaissa	Apr 9, 2018
KBNK Endgame	Nov 26, 2016
King	Feb 26, 2013
Knightmate Chess	Apr 20, 2015
KnockOut	Sep 20, 2016
Knowledge	Jul 22, 2017
KRK	Nov 26, 2016
Leonid Liberman	May 23, 2015
LL Chess	May 23, 2015
Losing Chess	Sep 18, 2017
Matant	Aug 14, 2013
Mate at a Glance	Sep 24, 2014
Mate Distance Pruning	Jun 2, 2017
Mate Killers	Feb 4, 2017
Mate Search	Oct 22, 2016
Mate-in-two	Oct 14, 2016
Mater	Apr 26, 2016
Mathieu Pagé	Feb 14, 2018
Matthew R. Brades	Jun 9, 2017
Mini Chess	Jun 7, 2013
MLChess	Jan 17, 2017
Mop-up Evaluation	Nov 26, 2016
Null Move Pruning	Dec 2, 2017
Overloading	May 5, 2017
Papa	Jan 11, 2018
Paradise	Nov 19, 2014
Perft	Sep 26, 2017
Perft Results	Feb 10, 2018
Piece Drop	Feb 20, 2018
Plymate	Jan 7, 2016
Proof-number search	Jan 22, 2018
python-chess	Nov 4, 2017
Repetitions	Jan 16, 2018
Retrograde Analysis	Mar 21, 2017
RISC 2500	Jan 7, 2016
Rolf C. Smith	Aug 25, 2014
Score	Apr 14, 2018
SEX Algorithm	Nov 25, 2014
Stalemate	Feb 21, 2018
Tactics	Jan 12, 2018
Terminal Node	Nov 17, 2012
Thompson's Databases	Dec 24, 2014
Transposition Table	Apr 19, 2018
Vice	Mar 8, 2016
Win at Chess	Sep 25, 2017
Winglet to include	Apr 25, 2015
Zwischenzug	Jan 15, 2014

Up one Level

Chess

GerdIsenberg — Sun, 21 Jan 2018 09:58:00 GMT

Home * Chess

		Chess, a two-player zero-sum abstract strategy board game with perfect information as classified by John von Neumann. Chess has an estimated state-space complexity of 1046 ^[1] , the estimated game tree complexity of 10123 is based on an average branching factor of 35 and an average game length of 80 ply ^[2] . This page is about the basic chess items, chessboard, pieces and moves, and how they are considered or encoded inside a chess program, to either represent a chess position inside its search and to play the game of chess. It sub-pages intersect with evaluation, board representation and even search topics.
Mark Wilkinson, Chess ^[3]

Board and Squares

Pieces and Moves

Color and Side

The Game of Chess

During the Game

The End

Chess Variants

Chess Problems

Chess and Mathematics

Chess Maxima

In 1966, Eero Bonsdorff, Karl Fabel, and Olvai Riihimaa gave 5899 as the maximum number of moves in a chess game ^[5] ^[6] ^[7]
Shirish Chinchalkar has determined a state-space complexity of 1046.25 as upper bound for the number of reachable chess positions ^[8], John Tromp gives about 10^45.888 ^[9] ^[10]
The maximum number of moves per chess position seems 218 ^[11] ^[12]

R6R/3Q4/1Q4Q1/4Q3/2Q4Q/Q4Q2/pp1Q4/kBNN1KB1 w - - 0 1

Chess and Psychology

Chess and Philosophy

Quote from Philosophy Looks at Chess ^[13] :

The game of chess has endured since at least the sixth century. Its earliest variant, the Indian game of Chaturanga, was from the beginning a game for thinkers. Since its inception, scholars, statesmen, strategists, and warriors have been fascinated by the game and its variants. German philosopher Emanuel Lasker and famed French artist Marcel Duchamp were both Grandmasters at chess. Karl Marx played chess avidly, as did Sir Bertrand Russell, Jean-Paul Sartre, and the logical positivist Max Black. Jean-Jacques Rousseau ^[14] mentions in his Confessions that, at the time, he "had another expedient, not less solid, in the game of chess, to which I regularly dedicated, at Maugis's, the evenings on which I did not go to the theater. I became acquainted with M. de Légal, M. Husson, Philidor, and all the great chess players of the day, without making the least improvement in the game." More recently, philosopher Stuart Rachels reports that his father, the late philosopher and prominent ethicist James Rachels, received a bribe from a Russian Grandmaster while he was the chair of the U.S. Chess Federation's Ethics committee.

Chess Programs called Chess

Chess the Northwestern University Chess Program by Larry Atkin and David Slate
Chess 0.5 by Larry Atkin and Peter W. Frey
Chess 0.5X by Wim Elsenaar
Chess 2001, Dedicated Chess Computers
Chess 201x by Filip Höfer
Chess-64 by Fabien Letouzey
Chess 7.0 by Larry Atkin

Publications

1949

Claude Shannon (1949). Programming a Computer for Playing Chess. pdf from The Computer History Museum

1950 ...

Claude Shannon (1950). A Chess-Playing Machine. Scientific American, Vol. 182 (No. 2, February 1950), pp. 48-51. Reprinted in The World of Mathematics, edited by James R. Newman, Simon & Schuster, NY, Vol. 4, 1956, pp. 2124-2133. Included in Part B
J. B. S. Haldane (1952). The mechanical chess-player. British Journal of Philosophy of Science, Vol. 3, No. 10
Alan Turing (1953). Chess. part of the collection Digital Computers Applied to Games. in Bertram Vivian Bowden (editor), Faster Than Thought, a symposium on digital computing machines, reprinted 1988 in Computer Chess Compendium, reprinted 2004 in Chapter 16 of The Essential Turing.

1955 ...

Paul Stein, Stanislaw Ulam (1957). Experiments in chess on electronic computing machines. Chess Review, 13 January 1957.
James Kister, Paul Stein, Stanislaw Ulam, William Walden, Mark Wells (1957). Experiments in Chess. Journal of the ACM, Vol. 4, No. 2
Allen Newell, Cliff Shaw, Herbert Simon (1958). Chess Playing Programs and the Problem of Complexity. IBM Journal of Research and Development, Vol. 4, No. 2, pp. 320-335
Alex Bernstein, Michael de V. Roberts (1958). Computer vs. Chess-Player. Scientific American, Vol. 198, pp. 96-105. pdf from The Computer History Museum, reprinted 1988 in Computer Chess Compendium
Alex Bernstein, Michael de V. Roberts, Timothy Arbuckle, Martin Belsky (1958). A chess playing program for the IBM 704. Proceedings of the 1958 Western Joint Computer Conference, pp. 157-159, Los Angeles, California. pdf from The Computer History Museum

1960 ...

Alan Kotok (1962). A Chess Playing Program for the IBM 7090, B.S. Thesis, MIT, AI Project Memo 41, Computation Center, Cambridge MA. pdf

1965 ...

Jack Good (1968). A Five-Year Plan for Automatic Chess. Machine Intelligence Vol. 2, pp. 110-115
Mikhail Botvinnik (1968). Algoritm igry v shakhmaty. (The algorithm of chess)

1970 ...

Georgy Adelson-Velsky, Vladimir Arlazarov, Alexander Bitman, Alexander Zhivotovsky, Anatoly Uskov (1970). Programming a Computer to Play Chess. Russian Mathematical Surveys, Vol. 25, pp. 221-262.

1975 ...

Ron Atkin, Ian H. Witten (1975). A Multi-Dimensional Approach to Positional Chess. International Journal of Man-Machine Studies, Vol. 7, No. 6
Ron Atkin, William Hartston, Ian H. Witten (1976). Fred CHAMP, Positional-Chess Analyst. International Journal of Man-Machine Studies, Vol. 8, No. 5
Donald Michie (1976). An Advice-Taking System for Computer Chess. Computer Bulletin, Ser. 2, Vol. 10, pp. 12-14. ISSN 0010-4531.

1980 ...

Aviezri Fraenkel, David Lichtenstein (1981). Computing a Perfect Strategy for n x n Chess Requires Time Exponential in N. Journal of Combinatorial Theory, Ser. A, Vol. 31, No. 2

1985 ...

Ingo Althöfer (1985). Das 3-Hirn - Entscheidungsteilung im Schach. Computerschach und Spiele, pp. 20-22 (German)
Ingo Althöfer (1989). A Survey of Some Results in Theoretical Game Tree Search and the 'Dreihirn'-experiment. Proceedings Workshop on New Directions in Game-tree Search, pp. 16-32. Edmonton, Canada.

1990 ...

Ingo Althöfer (1991). Selective trees and majority systems: two experiments with commercial chess computers. Advances in Computer Chess 6
Robert Levinson, Feng-hsiung Hsu, Tony Marsland, Jonathan Schaeffer, David Wilkins (1991). The Role of Chess in Artificial Intelligence Research. IJCAI 1991, pdf, also in ICCA Journal, Vol. 14, No. 3, pp. 153-161, pdf
Fernand Gobet, Peter Jansen (1994). Towards a Chess Program Based on a Model of Human Memory. Advances in Computer Chess 7

1995 ...

Ingo Althöfer (1997). A Symbiosis of Man and Machine Beats Grandmaster Timoshchenko. ICCA Journal, Vol. 20, No. 1
Ingo Althöfer (1997). On the k-best Mode in Computer Chess: Measuring the Similarity of Move Proposals. ICCA Journal, Vol. 20, No. 3
Ingo Althöfer (1998). LIST-3-HIRN vs. Grandmaster Yusupov. - A Report on a Very Experimental Match, Part I: The Games. ICCA Journal, Vol. 21, No. 1
Ingo Althöfer (1998). 13 Jahre 3-Hirn – Meine Schach-Experimente mit Mensch-Maschinen-Kombinationen. ISBN 3-00-003100-6. (German)

2000 ...

Ingo Althöfer (2001). Grandmaster Chess with one-sided Computer Help. ICGA Journal, Vol. 24, No.4
Marek Strejczek (2004). Some aspects of chess programming. Technical University of Łódź, Faculty of Electrical and Electronic Engineering, Department of Computer Science, Supervisor Maciej Szmit, zipped pdf, pdf
Henk Mannen, Marco Wiering (2004). Learning to play chess using TD(λ)-learning with database games. Cognitive Artiﬁcial Intelligence, Utrecht University, Benelearn’04

2005 ...

Fernand Gobet, Peter Jansen (2005). Training in Chess: A Scientific Approach. pdf
Aviezri Fraenkel (2006). Nim is Easy, Chess is Hard – But Why?? ICGA Journal, Vol. 29, No. 4, pdf
Diego Rasskin-Gutman (2009). Chess Metaphors - Artificial Intelligence and the Human Mind. ISBN-13: 978-0-262-18267-6, translated by Deborah Klosky, MIT Press ^[15]
Bernd Blasius, Ralf Tönjes (2009). Zipf's Law in the Popularity Distribution of Chess Openings. Physical Review Letters, 103, 218701, pdf ^[16]
Shay Bushinsky (2009). Deus Ex Machina— A Higher Creative Species in the Game of Chess. AI Magazine, Vol. 30, No. 3 » Machine Creativity ^[17]

2010 ...

Christian Hesse (2011). The Joys of Chess - Heroes, Battles & Brilliancies. ISBN: 978-90-5691-355-7, New In Chess ^[18]
Frédéric Prost (2012). On the Impact of Information Technologies on Society: an Historical Perspective through the Game of Chess. Turing-100. The Alan Turing Centenary, EPiC Volume 10
Matej Guid, Ivan Bratko (2012). Detecting Fortresses in Chess. Elektrotehniški vestnik, Vol. 79, Nos. 1-2, pdf » Rybka, Houdini ^[19]
Kristian Spoerer, Toshihisa Okaneya, Kokolo Ikeda, Hiroyuki Iida (2013). Further Investigations of 3-Member Simple Majority Voting for Chess. CG 2013
Katja Grace (2013). Algorithmic Progress in Six Domains. Technical report 2013-3, Machine Intelligence Research Institute, Berkeley, CA, pdf, 5 Game Playing, 5.1 Chess, 5.2 Go, 9 Machine Learning
Nick Pelling (2013). Chess Superminiatures. eBook, Kindle edition, Amazon
John Nunn (2014). Maths and Chess. ICGA Journal, Vol. 37, No. 4
Kenneth W. Regan, Tamal T. Biswas, Jason Zhou (2014). Human and Computer Preferences at Chess. pdf

2015 ...

Tamal T. Biswas, Kenneth W. Regan (2015). Measuring Level-K Reasoning, Satisficing, and Human Error in Game-Play Data. IEEE ICMLA 2015, pdf preprint
Vito Janko, Matej Guid (2015). Development of a Program for Playing Progressive Chess. Advances in Computer Games 14 ^[20]
Guy Haworth, Tamal T. Biswas, Kenneth W. Regan (2015). A Comparative Review of Skill Assessment: Performance, Prediction and Profiling. Advances in Computer Games 14
Muthuraman Chidambaram, Yanjun Qi (2017). Style Transfer Generative Adversarial Networks: Learning to Play Chess Differently. arXiv:1702.06762v1 ^[21] » Neural Networks
Lyudmil Tsvetkov (2017). The Secret of Chess. ^[22]
David Silver, Thomas Hubert, Julian Schrittwieser, Ioannis Antonoglou, Matthew Lai, Arthur Guez, Marc Lanctot, Laurent Sifre, Dharshan Kumaran, Thore Graepel, Timothy Lillicrap, Karen Simonyan, Demis Hassabis (2017). Mastering Chess and Shogi by Self-Play with a General Reinforcement Learning Algorithm. arXiv:1712.01815 » AlphaZero

Forum Posts

1989

Can Chess Help Adapt to Life? by Mike Valvo, rgc, September 06, 1989

1990 ...

Is chess in NP? by Antti Juhani Ylikoski, rec.games.programmer, May 26, 1997

2000 ...

Does this position blow up your program? by Mike Byrne, CCC, December 23, 2002
Subject: Maximum Number of Legal Moves by Andrew Shapira, CCC, May 08, 2005
Variants and Board Size by Harm Geert Muller, CCC, October 25, 2007

2010 ...

max amount of moves from a position? by Srdja Matovic, CCC, June 10, 2011
Contest: Find Position with the most moves by Charles Roberson, CCC, December 09, 2011
New chess variants by Ferdinand Mosca, CCC, March 03, 2012 » Chess Variants
Chess and the "Golden Ratio"... by Steve Maughan, CCC, December 19, 2012
Chess with incomplete information by Harm Geert Muller, CCC, December 13, 2013

2014

Total possible chess positions? by Matthew R. Brades, CCC, March 26, 2014
for Chess-variant authors by Harm Geert Muller, CCC, September 17, 2014 » Chess Engine Communication Protocol, WinBoard, XBoard
XBoard and chess variants by Evert Glebbeek, CCC, October 28, 2014
UCCI2WB by Harm Geert Muller, CCC, October 27, 2014 » Chinese Chess (Universal Chinese Chess Interface, UCCI)
UCI protocol for chess variants by Evert Glebbeek, CCC, October 28, 2014 » UCI

2015 ...

Most common chess variant? by Stefano Gemma, CCC, April 15, 2015 » Chess Variants
The future of chess and elo ratings by Larry Kaufman, CCC, September 20, 2015 » Match Statistics, Opening Book
Winboard 4.8.0b and Amazon chess variant by Ferdinand Mosca, CCC, December 05, 2015 » WinBoard
Matibay an amazon chess variant engine by Ferdinand Mosca, CCC, December 08, 2015
Masipag, a nightrider chess variant engine by Ferdinand Mosca, CCC, December 09, 2015

2016

Grande Acedrex by Harm Geert Muller, CCC, January 04, 2016
Tamerlane Chess by Harm Geert Muller, CCC, January 28, 2016
New chess variant by Evert Glebbeek, CCC, June 06, 2016 » Chess Variants
Max moves in a position by Laurie Tunnicliffe, CCC, October 22, 2016 » Chess Maxima

2017

Winboard variants online by Erin Dame, CCC, March 22, 2017 » Chess Variants, WinBoard
The Peace-Chess Challenge by Harm Geert Muller, CCC, September 24, 2017 » Chess Variants
Weakly vs strongly solving chess by Greg Simpson, CCC, September 26, 2017
best board representation for variants (javascript) ? by Mahmoud Uthman, CCC, December 10, 2017 » Board Representation, JavaScript

2018

Is modern chess software lossless or lossy? by Meni Rosenfeld, CCC, January 10, 2018 » Playing Strength, Selectivity
Is chess still 99% tactics? by Alvaro Cardoso, CCC, January 11, 2018 » Tactics
A Chess variant with low draw rate by Kai Laskos, CCC, January 19, 2018 » Chess Variants

External Links

Wikipedia

Chess from Wikipedia
Chess theory from Wikipedia
Computer chess from Wikipedia
First-move advantage in chess from Wikipedia
Outline of chess from Wikipedia
Rules of Chess from Wikipedia
School of chess from Wikipedia
Solving chess from Wikipedia
Glossary of chess from Wikipedia

Chess

Chess Variants

Misc

CHESS - Microsoft Research a tool for finding and reproducing Heisenbugs in concurrent programs.
Chess (musical) from Wikipedia
BBC World Service Programmes - The Friday Documentary: Seeking The Endgame, by Simon Terrington, with statements by David Levy et al. ^[23]
BBC - Future - The cyborg chess players that can’t be beaten by Chris Baraniuk, December 04, 2015 » David Levy, Boris Alterman, Shay Bushinsky, Mark Lefler
Mathematics and Chess Page
SFE - The Science Fiction Encyclopedia - Chess
Anthony Braxton Interview - Chess, Math & Music, YouTube Video
Marcel Duchamp on Chess, YouTube Video

References

^ Shirish Chinchalkar (1996). An Upper Bound for the Number of Reachable Positions. ICCA Journal, Vol. 19, No. 3, pp. 181-183
^ Victor Allis (1994). Searching for Solutions in Games and Artificial Intelligence. Ph.D. Thesis, University of Limburg, pdf, 6.3.9 Chess pp. 171
^ Tableaux ayant pour sujet les échecs
^ Seirawan chess from Wikipedia
^ Eero Bonsdorff, Karl Fabel, Olvai Riihimaa (1966) Schach und Zahl - Unterhaltsame Schachmathematik. Seite 11-13, Walter Rau Verlag, Düsseldorf (German)
^ 50-Züge-Regel - Schachmathematik from Wikipedia.de (German)
^ Defending Humanity's Honor by Tim Krabbé, see game NewRival - Faile with 493 moves, and playing 402 moves with bare kings!
^ Shirish Chinchalkar (1996). An Upper Bound for the Number of Reachable Positions. ICCA Journal, Vol. 19, No. 3
^ John's Chess Playground - Number of chess diagrams and positions
^ Re: Total possible chess positions? by Álvaro Begué, CCC, March 26, 2014
^ Does this position blow up your program? by Mike Byrne, CCC, December 23, 2002
^ Subject: Maximum Number of Legal Moves by Andrew Shapira, CCC, May 08, 2005
^ Philosophy Looks at Chess by Benjamin Hale
^ Jean-Jacques Rousseau and Chess by Edward Winter
^ Chess Metaphors – Artificial Intelligence and the Human Mind by Diego Rasskin-Gutman, ChessBase News, January 28, 2010
^ Zipf's law from WIkipedia
^ Machine creativity: what it is and what it isn't by Albert Silver, ChessBase News, August 28, 2016
^ The joys of chess – and the value of the pieces, ChessBase News, December 21, 2011
^ Re: Tony's positional test suite by Louis Zulli, CCC, August 01, 2017
^ Progressive chess from Wikipedia
^ Using GAN to play chess by Evgeniy Zheltonozhskiy, CCC, February 23, 2017
^ The Secret of Chess by Lyudmil Tsvetkov, CCC, August 01, 2017
^ BBC Computer Chess Radio Programme by Harvey Williamson, Hiarcs Forum, September 11, 2010

Up one Level

Chess Position

GerdIsenberg — Sun, 10 Sep 2017 16:57:20 GMT

Home * Chess * Position

		The Chess Position describes how pieces are placed on the chessboard, as printed as chess diagram, image or photograph from a game of chess. In 1996 Shirish Chinchalkar determined 1046 as upper bound for the number of reachable chess positions ^[1]. The maximum number of moves per chess position seems 218 ^[2]. Of course, the information of any arbitrary chess position which occurs inside the game of chess, might be determined from a certain initial starting position and a sequence of moves (half-moves), which leads to this position. Anyway, an efficient data structure for a chess position, which is incrementally updated during game play and search is essential for a chess playing program.
Marcel Duchamp ^[3] ^[4]

Specifying a Chess Position

Summary

Positions inside the Search

Positions

Notations

Flipping and Mirroring

Specifying a Chess Position

Except the determination of three fold repetitions, which requires the whole move record, at least from the last irreversible move (half-move) played, the chess position should keep track of various informations related to the position also for efficiency reasons. Another issue is to make chess positions persistent with a maximum of information required, but without the whole game history, as specified by the Forsyth-Edwards Notation or Extended Position Description.

Beside piece placement, as considered by the board representation, the side to move is essential, which might take only one bit inside an appropriate data structure for a chess position. Additionally, the Castling ability for both sides, as reflected by the castling rights and a possible en passant target square (or file) is needed to further completely specify the position, as well as the halfmove clock to cover the fifty-move rule.

Summary

A chess positions consists of

Piece placement on the Chessboard as considered by the Board Representation
Side to move
Castling rights
En passant target square
Halfmove Clock

Positions inside the Search

In the context of Search, a position is the node inside a search tree. To completely determine the position with respect to repetitions, one additionally needs a move list or any other appropriate data structure, to keep up to 100 reversible half-moves, likely associated with Zobrist keys of the intermediate positions.

Positions

Notations

Extended Position Description (EPD)
Forsyth-Edwards Notation (FEN)
Forsyth-Edwards Expanded Notation (FEEN)

Flipping and Mirroring

Publications

Jürg Nievergelt (1977). Information content of chess positions. ACM SIGART Newsletter 62, pp. 13-14. Reprinted as: Information content of chess positions: Implications for game-specific knowledge of chess players, pp. 283-289. Machine Intelligence 12 (eds. Jean Hayes Michie, Donald Michie, E. Tyugu). Clarendon Press, Oxford, 1991. ISBN 0-19-853823-5.
Bernhard Balkenhol (1994). Data Compression in Encoding Chess Positions. ICCA Journal, Vol. 17, No. 3, zipped ps
Shirish Chinchalkar (1996). An Upper Bound for the Number of Reachable Positions. ICCA Journal, Vol. 19, No. 3
Alex de Voogt (2002). Reproducing board game positions: Western Chess and African Bao. Swiss Journal of Psychology, Vol 61, No. 4

Forum Posts

1980 ...

compact representation of a position by Bill Vaughan, net.chess, January 5, 1982
compact representation of chess positions by Tom Truscott, net.chess, January 7, 1982 » Zobrist Hashing ^[5]

1990 ...

entropy of chess positions by John Tromp, rgc, April 15, 1991
estimated number of chesspositions by Vincent Diepeveen, rgcc, October 27, 1995
number of moves in position by Leonid, CCC, September 19, 1999
Re: number of moves in position by Leonid, CCC, September 21, 1999

2000 ...

Min # of bits needed to store a chess position by James Robertson, CCC, April 20, 2000
Minimum bits to encode a chess position by Ken Payson, The Math Forum @ Drexel University, February 8, 2002
Making positions in eps by Renze Steenhuisen, CCC, October 27, 2003 » Fen2eps

2010 ...

allowing invalid positions by Eric Langedijk, CCC, August 13, 2013
Counting endgame positions by Kirill Kryukov, CCC, January 08, 2014 ^[6]
Total possible chess positions? by Matthew R. Brades, CCC, March 26, 2014 » Chess Maxima

2015 ...

Binary FEN by J. Wesley Cleveland, CCC, July 24, 2015
Max moves in a position by Laurie Tunnicliffe, CCC, October 22, 2016 » Chess Maxima, Move List

External Links

Programmer Puzzle: Encoding a chess board state throughout a game from Stack Overflow
Chess Position Trainer by Stefan Renzewitz and Gregory Prentice
NULP in chess endgames by Kirill Kryukov

References

^ Shirish Chinchalkar (1996). An Upper Bound for the Number of Reachable Positions. ICCA Journal, Vol. 19, No. 3
^ Subject: Maximum Number of Legal Moves by Andrew Shapira, CCC, May 08, 2005
^ Marcel Duchamp: The Art of Chess
^ Marcel Duchamp: Chess Master Saint Louis University Museum of Art Saint Louis University : SLU
^ Re: Hashing function for board positions post 4 by Jim Gillogly, rgcc, May 12, 1997
^ NULP in chess endgames by Kirill Kryukov

What links here?

Page	Date Edited
2D Graphics Board	Sep 23, 2017
3D Graphics Board	Sep 23, 2017
Acornsoft Chess	Dec 11, 2016
AlphaZero	Feb 10, 2018
Analog Evaluation	Oct 27, 2017
Arminius	Aug 5, 2017
Atom Chess	Dec 11, 2016
B*	Nov 27, 2017
BCH Hashing	May 8, 2017
Bernhard Balkenhol	Oct 26, 2013
Beta-Cutoff	Oct 22, 2017
Bitboard Board-Definition	Jun 23, 2014
Board Representation	Dec 11, 2017
Bookbuilder	Feb 4, 2018
Bookup	Feb 4, 2018
Brainfish	Oct 8, 2017
Branching Factor	Jun 28, 2017
CAPS	Dec 23, 2017
Castling	May 5, 2017
Castling rights	Jan 7, 2017
CHEOPS	Apr 18, 2015
Cheops (Miller)	Jan 13, 2017
Chess	Jan 21, 2018
Chess Game	Mar 28, 2017
Chess Position	Sep 10, 2017
Chessboard	May 10, 2017
ChessBrain	Jun 28, 2017
ChessV	Jan 21, 2018
ChessX	Feb 26, 2015
Chunker	Jul 12, 2016
Chunking	Jun 12, 2017
Color	Mar 12, 2014
Color Flipping	May 17, 2017
Combination	Oct 25, 2016
Copy-Make	May 23, 2017
CTG	Aug 22, 2016
Dabbaba	Oct 21, 2014
Data	Nov 26, 2017
Databases	Mar 18, 2018
Deep Learning	Feb 12, 2018
Diagonal Mirroring	Jun 29, 2013
Doch	May 23, 2017
Dragan Zdravkovic	Nov 29, 2013
Dragon FR	Sep 9, 2016
Dynamic Programming	Feb 11, 2018
Dynamic Tree Splitting	Apr 10, 2017
Edwards' Tablebases	Sep 26, 2016
Efficient Generation of Sliding Piece Attacks	Nov 5, 2016
En passant	Jan 16, 2018
Eval Tuning in Deep Thought	Jun 7, 2016
Evaluation	Feb 1, 2018
Extended Position Description	Dec 2, 2017
Eye Movements	Jul 22, 2015
Fail-High Reductions	Mar 6, 2014
Ferdinand Mosca	Jul 28, 2017
Forsyth-Edwards Expanded Notation	Aug 31, 2015
Forsyth-Edwards Notation	Sep 10, 2017
George Baylor	Sep 22, 2014
Gerard Zielinski	Sep 25, 2014
Graph History Interaction	Oct 16, 2017
Graphics Programming	Dec 22, 2017
Grit Lachmann	Apr 26, 2014
Halfmove Clock	Aug 9, 2017
Horizontal Mirroring	Jun 29, 2013
Hypra-Chess	Oct 28, 2017
Incremental Updates	Sep 6, 2017
Initial Position	Apr 14, 2018
Irreversible Moves	Jan 25, 2014
Iteration	May 5, 2017
Jacques Pitrat	Aug 7, 2015
James Robertson	Jun 5, 2016
Jan Renze Steenhuisen	Sep 10, 2017
Jerry	Mar 28, 2016
John Tromp	Jan 6, 2017
Kvetka	Mar 28, 2016
LittleBlitzer	Jan 24, 2017
Lozza	Apr 18, 2018
Make Move	Mar 2, 2016
MAPP	Jan 30, 2016
Mater	Apr 26, 2016
Move List	Jul 19, 2017
Moves	Feb 19, 2018
Much	Jun 7, 2016
MVC to include	May 7, 2011
Neural MoveMap Heuristic	Sep 24, 2015
Neural Networks	Mar 12, 2018
Node	Jul 20, 2015
Nodes per second	Feb 28, 2018
Occam	Jan 21, 2016
Papa	Jan 11, 2018
Paradise	Nov 19, 2014
Path-Dependency	Oct 16, 2017
Pattern Recognition	Sep 8, 2017
Pawn Push	Mar 27, 2010
Persistent Hash Table	Dec 31, 2017
Piece Recognition	Sep 8, 2017
Programming	Dec 16, 2017
Pseudo-Legal Move	May 23, 2015
Quiescence Search	Aug 19, 2017
Repetitions	Jan 16, 2018
RetroChess	Feb 2, 2014
Retrograde Analysis	Mar 21, 2017
Reversible Moves	Mar 13, 2010
Richard Lang	Jan 7, 2016
Robert A. Wagner	Oct 28, 2013
Root	Sep 26, 2016
Ruslan Hajiev	Oct 2, 2014
Scid	Apr 15, 2017
Scid on the Go	Jan 26, 2015
Score	Apr 14, 2018
Search	Feb 1, 2018
Search Explosion	Mar 30, 2017
Search Tree	Dec 23, 2016
Sensory Board	Mar 1, 2018
SEX Algorithm	Nov 25, 2014
Shirish Chinchalkar	Mar 26, 2014
Shu Yokoyama	Oct 25, 2017
Side to move	Oct 29, 2017
Simona Tancig	Nov 7, 2012
Stockfish	Apr 7, 2018
Symbolic	May 8, 2017
Tactics	Jan 12, 2018
Temporal Difference Learning	Feb 20, 2018
Texel's Tuning Method	Dec 2, 2017
Transposition	Jun 8, 2015
Transposition Table	Apr 19, 2018
Turochamp	Dec 14, 2017
Unmake Move	Jun 10, 2017
User Interface	Feb 21, 2018
Vertical Flipping	Oct 10, 2013
Vincent David	Oct 20, 2016
William Chase	Jan 21, 2016
Winglet to include	Apr 25, 2015
Winter	Jan 23, 2018
Zobrist Hashing	Jan 22, 2018

Up one Level

Chess Problems, Compositions and Studies

GerdIsenberg — Mon, 19 Feb 2018 21:52:08 GMT

Studies in CPW

Chess Composer

See also

Selected Publications

Home * Chess * Problems, Compositions and Studies

A Chess Problem or Composition, set by a composer, is presented to (human) solvers with a particular task to be achieved. Chess problems include the sub-genre of directmates, helpmates and selfmates in a pre-determined number of moves, and retrograde analysis problems. Beside chess problems in classical or orthodox chess, Fairy chess offers an own branch of problem solving. Unlike problems, which often present very artificial looking positions, Studies or endgame studies often appear that they could occur in a game, and represent a sort of puzzle, usually not requiring a solution in a fixed number of moves. Dedicated chess problem and composition software is used as composition tool, and to prove correctness and uniqueness of chess problems. Chess aesthetics or beauty in chess is generally appreciated by both players and composers, awarded in certain championships also in the world of chess composition.

Studies in CPW

Chess Composer

To expand this list, create a new page with the tag "composer".

Selected Publications

1960 ...

Vladimir E. Alekseev (1969). Compilation of Chess Problems on a Computer. Technical translation FSTC-HT-23-124-69, US Army, NTIS AD 689470 (Problemy Kibernetiki, 19, 1967)

1970 ...

Martin Gardner (1979). Chess Problems on a Higher Plane, Including Mirror Images, Rotations and the Superqueen. Scientific American, Vol. 270
Donald Michie (1979). The Computer Attacks Moravec Problem. Personal Computing, Vol. 3, No. 10, pp. 73 ^[1]
Editor (1979). Chess Ratings from Problem Solving. Personal Computing, Vol. 3, No. 12, pp. 77 » CAPS II, Playing Strength

1980 ...

Walter Korn (1980). Electronic Chess: Changing Aesthetics and Mores. Personal Computing, Vol. 4, No. 7, pp. 74
John Roycroft (1981). The Chess Endgame Study. Dover Publications Inc., New York
László Lindner (1982). How the Computer Helps the Composer. ICCA Newsletter, Vol. 5, No. 2
Norman A. Macleod (1983). Is the Computer Going to Take Over from the Composer? ICCA Newsletter, Vol. 6, No. 2
László Lindner (1983). Experience with the Second Human-Computer Problem Test. ICCA Journal, Vol. 6, No. 3

1985 ...

Göran Grottling (1985). Problem-Solving Ability Tested. ICCA Journal, Vol. 8, No. 2
László Lindner (1985). A Critique of Problem-Solving Ability. ICCA Journal, Vol. 8, No. 3
László Lindner (1985). A Test to Compare Human and Computer Fairy-Chess Problem Solving. ICCA Journal, Vol. 8, No. 3
Paul Wiereyn (1985). Problem-Solving Ability Tested II. ICCA Journal, Vol. 8, No. 3
Paul Wiereyn (1985). Inventive Problem Solving. ICCA Journal, Vol. 8, No. 4
László Lindner (1985). Problem Solving: The Present and Possibilities for Development. Advances in Computer Chess 4
Henk le Grand (1986). The Impact of Computers on Chess-Problem composition. ICCA Journal, Vol. 9, No. 3
Michael Schlosser (1988). Computers and Chess-Problem Composition. ICCA Journal, Vol. 11, No. 4
László Lindner (1989). Performance Improvements in Problem-Solving Programs since 1984. Advances in Computer Chess 5

1990 ...

László Lindner, Michael Schlosser (1991). New Ideas in Problem Solving and Composing Programs. Advances in Computer Chess 6
Michael Schlosser (1991). Can a Computer Compose Chess Problems? Advances in Computer Chess 6
Brian Gosling (1992). Chess computers and endgame studies. ICCA Journal, Vol. 15, No. 1
Jan van Reek, Henk van Donk (1992). History of endgame study composing in the Netherlands and Flanders. ARVES. ISBN 90-72939-12-3
Rainer Staudte, U. Erdmenger (1994). Hilfsmattaufgaben als arithmetische Constraints In: N.E. Fuchs, G. Gottlob: Proceedings of the Tenth Logic Programming Workshop, WLP 1994, Universität Zürich, Berichte des Institutes für Informatik, Nr. 94.10.
Michael Schlosser (1994). Können Computer Schachprobleme komponieren? Teil 1: Deutsche Schachblätter/Schach-Report, 143(1994)5, S. 53-55 Teil 2: Deutsche Schachblätter/Schach-Report, 143(1994)6, S. 57-60

1995 ...

Richard K. Guy, John Roycroft, Kenneth Solja (1996). Richard Guy's Chess Endgame Studies. Prime Actions
Rainer Staudte (1997). Constraints for Solving Helpmates. Advances in Computer Chess 8, ps
M. Hirose, Hitoshi Matsubara, T. Itoh (1997). The Composition of Tsume-Shogi Problems. Advances in Computer Chess 8
Paul Wiereyn (1997). Genius-3 Cooked Endgame Studies. ICCA Journal, Vol. 20, No. 3
Makoto Sakuta, Hiroyuki Iida (1999). Solving Problems with Uncertainty: A case study using Tsuitate-Tsume-Shogi. Proceedings of Game Programming Workshop in Japan '99, pp. 145-152, Hakone, Japan, pdf
Noam D. Elkies (1999). On numbers and endgames: Combinatorial game theory in chess endgames. pdf, differs only in trivial stylistic details from the (1996) version published in Games of No Chance edited by Richard J. Nowakowski

2000 ...

Harold van der Heijden (2001). Endgame Tables and Endgame Study Composition. ICGA Journal, Vol. 24, No. 2
Noam Elkies (2001). Endgame Tables and Chess Composition. ICGA Journal, Vol. 24, No. 2
Michael Schlosser, Rainer Staudte, Manfred Zucker (2002). 90 Jahre Schachkomposition in Chemnitz, (German) pdf

2005 ...

Noam Elkies (2005). New directions in enumerative chess problems. Electronic Journal of Combinatorics, Vol. 11, No. 2, arXiv:math/0508645 ^[2]
Azlan Iqbal, Mashkuri Yaacob (2006). A Systematic and Discrete View of Aesthetics in Chess. Journal of Comparative Literature and Aesthetics, Vol. XXIX, Nos. 1-2
Fridel Fainshtein (2006). An Orthodox k-Move Problem-Composer for Chess Directmates. M.Sc. thesis, Bar-Ilan University, pdf ^[3]
Fridel Fainshtein, Yaakov HaCohen-Kerner (2006). A Chess Composer of Two-Move Mate Problems. ICGA Journal, Vol. 29, No. 1, pdf
Yaakov HaCohen-Kerner, Fridel Fainshtein (2006). A Deep Improver of Two-move Chess Mate Problems. Cybernetics and Systems, Vol. 37, No. 5
Gady Costeff (2006). How I Became A Great Composer. EG, Vol. 11, 159-163, ARVES, pdf
Azlan Iqbal, Mashkuri Yaacob (2008). Theme Detection and Evaluation in Chess. ICGA Journal, Vol. 31, No. 2
Azlan Iqbal, Mashkuri Yaacob (2008). Advanced Computer Recognition of Aesthetics in the Game of Chess. WSEAS Transactions on Computers, Vol. 7, Issue 5, pdf
Torsten Linß (2008). Databases for Chess Problems. Workshop Chess and Mathematics

2010 ...

Matej Guid (2010). Search and Knowledge for Human and Machine Problem Solving. Ph.D. thesis, University of Ljubljana, pdf ^[4]
Azlan Iqbal, Harold van der Heijden, Matej Guid (2010). Research Grant to Investigate Multi-Dimensional Aesthetic Perception using Endgame Studies. EG, Alexander Rueb Vereniging voor Schaakeindspelstudie (ARVES), No. 180, Vol. XVI ^[5]
Azlan Iqbal (2010). Aesthetics in Mate-In-3 Combinations, Part I Combinatorics and Weights, ICGA Journal, Vol. 33, No. 3
Azlan Iqbal (2010). Aesthetics in Mate-In-3 Combinations, Part II Normality, ICGA Journal, Vol. 33, No. 4

2011

Azlan Iqbal (2011). Increasing Efficiency and Quality in the Automatic Composition of Three-Move Mate Problems. Entertainment Computing - ICEC 2011, Lecture Notes in Computer Science, Vol. 6972, Springer. ISBN 978-3-642-24499-5
Guy Haworth, Eiko Bleicher, Harold van der Heijden (2011). Uniqueness in Chess Studies. ICGA Journal, Vol. 34, No. 1
Guy Haworth, Harold van der Heijden, Eiko Bleicher (2011). Zugzwangs in Chess Studies. ICGA Journal, Vol. 34, No. 2
Guy McCrossan Haworth, Árpád Rusz (2011). Position Criticality in Chess Endgames. Advances in Computer Games 13, pdf

2012

Azlan Iqbal, Harold van der Heijden, Matej Guid, Ali Makhmali (2012). Evaluating the Aesthetics of Endgame Studies: A Computational Model of Human Aesthetic Perception. IEEE Transactions on Computational Intelligence and AI in Games, Vol. 4, No. 3 ^[6]

Blog & Forum Posts

2000 ...

Chess problem solving by Timo Saari, CCC, October 04, 2001
Test Position = Study by David Przepiorka [Vorwärts, 1910] by José Antônio Fabiano Mendes, CCC, February 05, 2004

2010 ...

Troitzky, 1930 by Jesús Muñoz, CCC, March 25, 2013
Draw by stalemate (Campbell, easy position for engines) by Jesús Muñoz, CCC, July 31, 2013 » Stalemate
Study solved by Carlsen by Jesús Muñoz, CCC, August 15, 2013
Helpmate-programs - and some problems for you.... by Jens Bæk Nielsen, CCC, August 26, 2013
First prize for studies in Šachová skladba 2011-12 by Jesús Muñoz, CCC, August 20, 2014

2015 ...

Wrong chess studies by Lyudmil Antonov, CCC, February 21, 2015
Penrose Puzzle by Erin Dame, CCC, March 14, 2017 » Penrose Puzzle
A Coup(e) of Duchamp by Ken Regan, Gödel's Lost Letter and P=NP, February 16, 2018
Marcel Duchamp endgame "splits" engines / hash phenomenon by Kenneth Regan, CCC, February 19, 2018 » Marcel Duchamp, Transposition Table

External Links

Endgame Studies

General

Endgame study from Wikipedia
ARVES - Home (Alexander Rueb Vereniging voor SchaakEindspelStudie)
Chess Composition in TORUN by Marek Kwiatkowski
Chess Endgame Study Composition by Árpád Rusz
EG (magazine) from Wikipedia
EG issues from ARVES
Practical Chess Endgame + Computer Analysis by Brian Gosling

Studies

Problem Blogs

chess-problems-gr

Schwalbe

Software

Misc

Penrose Puzzle

» Roger Penrose, Penrose institute puzzle #1 • lichess.org ^[7]

Can you solve the chess problem which holds key to human consciousness? by Sarah Knapton, The Telegraph, March 14, 2017 ^[8]
Humans Can Solve This Chess Puzzle, But A Supercomputer Can't by Tom Hale, IFLScience, March 14, 2017
Sure you're not a robot? Solve this chess puzzle and prove it by Lance Ulanoff, Mashable, March 14, 2017
Will This Position Help Understand Human Consciousness? by Peter Doggers, Chess.com, March 15, 2017
A chess problem holds the key to human consciousness? by Frederic Friedel, ChessBase News, March 16, 2017
Can You Solve This Chess Puzzle That AI Software Can't? by Terry Berman, Interesting Engineering, March 19, 2017

References

^ www.arves.org - Moravec, Josef 1882-1969
^ This article is based on a presentation given at the banquet in honor of Richard Stanley's 60th birthday, and is dedicated to Stanley on this occasion
^ MatPlus.Net - General => Computers & chess problems ?
^ Dap Hartmann (2010). How can Humans learn from Computers? Review on Matej Guid's Ph.D. thesis, ICGA Journal, Vol. 33, No. 5
^ Dr. Mohammed Azlan Bin Mohamed Iqbal (Publications and Research Grants)
^ A computer program to identify beauty in problems and studies, ChessBase News, December 15, 2012
^ The Penrose Institute | Human and Artificial Intelligence
^ Penrose Puzzle by Erin Dame, CCC, March 14, 2017

What links here?

Page	Date Edited
Alybadix	Apr 26, 2016
APwin	Oct 12, 2017
Árpád Rusz	Oct 9, 2017
Brian Gosling	Apr 26, 2014
CAPS	Dec 23, 2017
Checkmate	Apr 13, 2018
Chess	Jan 21, 2018
Chess Problem Solving Engines	Apr 21, 2017
Chess Problems, Compositions and Studies	Feb 19, 2018
Chest	Mar 3, 2015
Composer	Sep 3, 2017
Draw Evaluation	Mar 12, 2018
Emil Vlasák	Sep 30, 2015
Erin Dame	Dec 2, 2017
Frederic Friedel	Jan 6, 2018
Fridel Fainshtein	Oct 8, 2014
Gady Costeff	May 30, 2014
George Georgopoulos	Aug 29, 2013
Gustav	May 14, 2016
Harold van der Heijden	Jan 8, 2014
Heiner Marxen	Apr 19, 2014
Henk le Grand	Apr 26, 2014
Ilkka Blom	Mar 3, 2015
Jan van Reek	Aug 18, 2016
Jean-Luc Seret	Jan 7, 2016
John Nunn	Dec 9, 2017
John Roycroft	Apr 24, 2016
José Antônio Fabiano Mendes	Feb 25, 2014
Juha Kasanen	Jan 7, 2016
Kenneth Wingate Regan	Feb 19, 2018
László Lindner	Sep 2, 2017
Ludwig Zagler	Sep 6, 2017
Makoto Sakuta	Dec 22, 2016
Marek Kwiatkowski	Oct 22, 2017
Mathematician	Apr 9, 2018
Michael Schlosser	Nov 15, 2016
Mika Korhonen	Jan 7, 2016
Mike Clarke	May 23, 2016
Noam Elkies	Apr 6, 2017
Norman A. Macleod	Sep 3, 2017
Olaf Jenkner	May 14, 2016
Paul Wiereyn	Jun 4, 2015
People	Feb 28, 2018
Playing Strength	Mar 31, 2018
Popeye	Oct 11, 2017
Rainer Staudte	Apr 26, 2014
Retrograde Analysis	Mar 21, 2017
Richard K. Guy	Jan 11, 2014
Scid on the Go	Jan 26, 2015
Stalemate	Feb 21, 2018
Test-Positions	Feb 25, 2018
Timo Saari	Jan 7, 2016
Torsten Linß	Nov 8, 2016
Václav Kotěšovec	May 14, 2016
Yaakov HaCohen-Kerner	Aug 23, 2014
Zugzwang	Dec 8, 2017

Up one Level

Chess Psychology Booklist

GerdIsenberg — Thu, 11 Apr 2013 10:22:35 GMT

Home * Knowledge * Psychology * Booklist

Blindfold Chess. History, Psychology, Techniques, Champions, World Records, and Important Games. Eliot Hearst and John Knott. McFarland and Company. 2009. 437 pages.
Chess: A Psychiatrist Matches Wits with Fritz. Ernest Pecci ^[1]^[2], MD. Pavior Publishing. 2001. 412 pages. amazon
Chess for Tigers. Simon Webb. Maxwell Macmillan Chess. 1991. 120 Pages. amazon.uk
Chess Master at Any Age. Rolf Wetzell. Thinkers’ Press. 1994. 300 pages. amazon
Chess Players’ Thinking. Pertti Saariluoma. Routledge. 1995. 201 pages. amazon
Chess Psychology. Angus Dunnington. Everyman Chess. 2003. 128 pages. google books
Chess. The Mechanics of the Mind. Pfleger and Treppner. 1988. 156 pages. amazon.de
Dynamics of Chess Psychology. Cary Utterberg. Chess Digest. 1994. 219 pages. Dynamics of Chess Psychology from Schachversand Niggemann
How to Become a Candidate Master. Alex Dunne. Thinkers’ Press. 1985. 252 pages. amazon
Moves in Mind. The Psychology of Board Games. Gobet et al. Psychology Press. 2004. 273 pages. amazon
Perception and Memory in Chess. Studies in the Heuristics of the Professional Eye. Adriaan de Groot & Fernand Gobet. Van Gorcum. 1996. 315 pages.
Philosophy Looks at Chess. Edited by Benjamin Hale. Open Court. 2008. 236 pages. review
Practical Chess Psychology. Amatzia Avni. Batsford. 2001. 160 pages. chesscafe.com
Predicament in 2 Dimensions. Ariel Mengarini. Thinkers’ Press. 1979. 105 pages. amazon.uk
Psychology in Chess. Nikolai Krogius. RHM Press. 1976. 243 pages. amazon
Schachpsychologie. Reinhard Munzert. Beyer Verlag. 1998. 390 pages. amazon.de
Secrets of a Grandpatzer. Malibu Chess Press. Kenneth Colby. 1979. 139 pages. amazon
The Art of Learning. An Inner Journey to Optimal Performance. Josh Waitzkin. Free Press. 2007. 265 pages. amazon
The Chess Mind. Cranberg and Albert. Guilford Press. 1988. 190 pages.
The Chess Mind. Gerald Abrahams. A Penguin Handbook. 1960. 346 pages. National Library Of Australia
The Genius and the Misery of Chess. Zhivko Kaikamjozov. Mongoose Press. 2008. 224 pages. amazon.uk
The Grandmaster’s Mind. Amatzia Avni. Gambit. 2004. 176 pages. amazon
The Inner Game of Chess. How to Calculate and Win. Andrew Soltis. McKay Chess Library. 1995. 359 pages. amazon
The Psychology of Chess Skill. Dennis Holding. Lawrence Erlbaum Associates. 1985. 271 pages. amazon
The Psychology of Chess. Hartston and Wason. Facts on File. 1984. 138 pages. amazon
The Psychology of the Chess Player. Reuben Fine. Dover. 1967. 74 pages. amazon
Think Like a Grandmaster. Kotov. Batsford. 1994. 200 pages. amazon
Thought and Choice in Chess. A. D. De Groot. Basic Books. 1965. 463 pages. amazon
Train Like a Grandmaster. Kotov. Batsford. 1981. 124 pages. amazon
Winning Chess Psychology. Wilf Holloway. Schachfirma Fruth. 1997. 212 pages.
Winning Chess Psychology 2. Wilf Holloway. 233 pages, see Wilfred Holloway from Schachversand Niggemann
Winning with Chess Psychology. Benko and Hochberg. McKay Chess Library. 1991. 264 pages. amazon

References

^ CHESS: A psychiatrist matches wits with Fritz - review from ChessBase, May 18, 2002
^ Chessgames of Ernest F Pecci from chessgames.com

Up one Level

Chess Query Language

GerdIsenberg — Mon, 08 Jan 2018 09:06:09 GMT

Home * Chess * Chess Query Language

The Chess Query Language (CQL) is a structured query language to search for games, problems, and studies that match specific themes from a collection in Portable Game Notation. CQL was developed by Gady Costeff and Lewis Stiller. It is Copyright (c) 2003-2018 and is free. The CQL Manual is hosted by the Internet Archive ^[1] ^[2] .

The current version is 5.1 and the documentation and download of the executable can be found on the website of Gady Costeff ^[3].

Sample query

^[4] ^[5]

;; look for positions where a rook circles in a 4x3 rectangle
;; we use the rectangle g2, d2, d6, g6 together with shift and flip
;;
(match :pgn input.pgn
       :output output.pgn
       :forany piece [Rr]
       (position
        $piece[g2]
        :and (
              (position :gappedsequence ((position :movefrom $piece[g6,d2] :moveto ?g2)))
              (position :gappedsequence ((position :movefrom $piece[d6,g2] :moveto ?d2)))
              (position :gappedsequence ((position :movefrom $piece[d6,g2] :moveto ?g6)))
              (position :gappedsequence ((position :movefrom $piece[g6,d2] :moveto ?d6)))
             )
        :shift
        :flip
       )
)

Publications

Gady Costeff (2004). The Chess Query Language: CQL. ICGA Journal, Vol. 27, No. 4, pdf

Forum Posts

CQL Users? by Guy Haworth, CCC, August 11, 2004
CQL - Stalemate with 2 pieces pinned by James Constance, CCC, July 17, 2005
Chess Query Language by David Dahlem, CCC, August 13, 2011
Chess Query Language by Giovanni Lavorgna, CCC, May 07, 2016
Scid vs PC with CQL , build issue by Steven Atkinson, CCC, November 25, 2017 » Scid vs. PC

External Links

CQL Introduction by Gady Costeff
CQL Manual hosted by the Internet Archive
Chess Query Language from Tim Krabbé's Chess Site
Chess Query Language from Wikipedia
CQL VisualCQL by Emil Vlasák

References

^ Chess Query Language by Giovanni Lavorgna, CCC, May 07, 2016
^ CQL Manual hosted by the Internet Archive
^ CQL Introduction by Gady Costeff
^ Sample CQL files (Internet Archive)
^ An html version of rookrectangle.cql (Internet Archive)

What links here?

Page	Date Edited
Chess	Jan 21, 2018
Chess Assistant	Jul 16, 2017
Chess Query Language	Jan 8, 2018
ChessBase (Database)	Feb 26, 2018
ChessX	Feb 26, 2015
Databases	Mar 18, 2018
Dictionary	Aug 24, 2017
Gady Costeff	May 30, 2014
ICGA Journal	Dec 21, 2017
Jose	Feb 26, 2015
Languages	Nov 26, 2017
Lewis Stiller	Oct 11, 2016
Portable Game Notation	Jan 11, 2018
Scid	Apr 15, 2017
Scid vs. PC	Jan 21, 2018
Scidb	Mar 18, 2018

Up one Level

Chessboard

GerdIsenberg — Wed, 10 May 2017 14:37:12 GMT

Home * Chess * Chessboard

		The Chessboard is the playing ground for the game of chess and its up to 16 white and black pieces each. It consists of 64 squares, eight rows, called ranks, times eight columns, called files. The squares are alternating dichromatic (light or white, and dark or black squares) on ranks as well on files. Ranks are labeled from '1' to '8', the files from 'A' to 'H' (or with lower case letters 'a' to 'h'), so that each square can be uniquely addressed via concatenated file- and rank labels. The lower left square with the "Address" 'a1' is dark. The diagonals are the north-east directed, distinguished from the anti-diagonals in north-east directions. Inside a chess program, the chessboard and its piece placement as chess position is subject of the board representation.
Marcel Duchamp, Homage to Caissa, 1965 ^[1]

Fourfold Symmetry

The chessboard is fourfold symmetrical with respect to rotation about an axis, based on the reflection symmetry of a square (not square of a chessboard but the whole board here). The four axis are the vertical line between the two center-files 'D' and 'E', the horizontal line between the 4th and 5th rank, and the main-diagonal and main-anti-diagonal. The orthogonal symmetrical squares have different, the diagonal symmetrical squares have same square-colors.

Publications

Martin Gardner (1973). Mathematical Games: How to Turn a Chessboard into a Computer to Calculate with Negabinary Numbers. Scientific American, Vol. 228, No. 4 ^[2]
Joachim H. Ahrens (1981). Paving the Chessboard. Journal of Combinatorial Theory, Series A, Vol. 31, No. 3
Noam Elkies (2002). Higher Numbers in pawn endgames on large chessboards. More Games of No Chance edited by Richard J. Nowakowski

External Links

Chessboard from Wikipedia
Wheat and chessboard problem
A Mathematical Chessboard Paradox by Christian Hesse, ChessBase News, March 24, 2009

References

What links here?

Page	Date Edited
2D Graphics Board	Sep 23, 2017
3D Graphics Board	Sep 23, 2017
Anti-Diagonals	Sep 2, 2012
Bit	Oct 29, 2012
Bitboards	Nov 14, 2017
Board Representation	Dec 11, 2017
Breakthrough (Game)	Aug 11, 2017
Captures	Oct 1, 2017
Center	Jun 21, 2016
Chess	Jan 21, 2018
Chess Position	Sep 10, 2017
Chessboard	May 10, 2017
ChessX	Feb 26, 2015
Combinatorial Logic	Apr 6, 2017
Complexity to include	Jun 16, 2011
Connectivity	Mar 6, 2016
Dedicated Chess Computers	Feb 20, 2018
Delfi	Jan 7, 2016
Diagonals	Jan 16, 2013
Dictionary	Aug 24, 2017
Direction	Oct 6, 2016
Distance	Sep 25, 2015
Djinn	Feb 8, 2016
Dumb7Fill	May 27, 2016
Edwards' Tablebases	Sep 26, 2016
Efficient Generation of Sliding Piece Attacks	Nov 5, 2016
Encoding Moves	Mar 27, 2016
Endianness	Jan 25, 2015
Files	Nov 22, 2015
Flipping Mirroring and Rotating	Oct 14, 2016
Glaurung	Mar 14, 2017
GUI	Mar 16, 2018
HeavyChess	Feb 14, 2014
Influence Quantity of Pieces	Jul 21, 2017
Lines of Action	Feb 5, 2018
Mobility	Jan 17, 2018
Nexus	Jan 7, 2016
Perceiver	Nov 21, 2017
Pertti Saariluoma	Jun 13, 2017
Piece Recognition	Sep 8, 2017
Piece-Lists	Feb 13, 2017
Pseudo-Legal Move	May 23, 2015
Ranks	Dec 15, 2008
Raspberry Turk	Sep 7, 2017
Repetitions	Jan 16, 2018
Sensory Board	Mar 1, 2018
Sjaak (Glebbeek)	Oct 4, 2017
Smirf	Apr 10, 2016
Square Mapping Considerations	Feb 28, 2018
Squares	Feb 15, 2015
Thompson's Databases	Dec 24, 2014
Vector Attacks	Dec 15, 2017
Winter	Jan 23, 2018

Up one Level

Color

GerdIsenberg — Wed, 12 Mar 2014 17:00:31 GMT

Home * Chess * Color

		In Chess, Color refers to the color of the two piece sets, the color each player is assigned to, the side to move and the color of a square. The pieces are divided, into white and black sets, but their colors should not taken literally. The players are referred to as "White" and "Black", they control their associated pieces. The colors of the sixty-four squares alternate and are referred to "light squares" and "dark squares", sometimes also referred to "White" and "Black" squares.
M. C. Escher, Day and Night, 1938 ^[1]

Color Definition

Since there are only two colors, one bit is sufficient to encode them. This is how one may define colors in C++:

enum enumColor {
   ecWhite = 0,
   ecBlack = 1
};

Toggle Color

Since the players alternately move, one need to toggle the side to move color after each move made inside the Chess Position object. This can be done by subtracting color from one (ecBlack), ...

inline enumColor toggleColor(enumColor color) {
   return ecBlack - color;
}

... or a little bit cheaper by xoring with the color with one (ecBlack).

inline enumColor toggleColor(enumColor color) {
   return color ^ ecBlack;
}

External Links

References

^ Picture gallery "Switzerland and Belgium 1935 - 1941" from The Official M.C. Escher Website

What links here?

Page	Date Edited
AlphaZero	Feb 10, 2018
Bishop Pair	Sep 10, 2017
Bit	Oct 29, 2012
Bitboard Board-Definition	Jun 23, 2014
Bitboards	Nov 14, 2017
Checks and Pinned Pieces (Bitboards)	Aug 14, 2013
Chess	Jan 21, 2018
Color	Mar 12, 2014
Color Flipping	May 17, 2017
Color of a Square	May 24, 2015
Color Weakness	Nov 24, 2017
Dictionary	Aug 24, 2017
Doubled Pawn	Mar 27, 2017
Duo Trio Quart (Bitboards)	Aug 18, 2017
Efficient Generation of Sliding Piece Attacks	Nov 5, 2016
Endgame	Sep 18, 2017
Files	Nov 22, 2015
Generic Programming	Jul 7, 2012
Material	Mar 31, 2018
Open file	Feb 15, 2015
Pawn Pushes (Bitboards)	Apr 5, 2013
Pertti Saariluoma	Jun 13, 2017
Piece-Lists	Feb 13, 2017
Piece-Square Tables	Mar 31, 2018
Promotion Square	Aug 15, 2011
Promotions	Jun 6, 2017
Pseudo-Legal Move	May 23, 2015
Ralph Betza	Mar 12, 2014
Ranks	Dec 15, 2008
Side to move	Oct 29, 2017
Simona Tancig	Nov 7, 2012
Weak Pawns	Dec 19, 2013

Up one Level

Color of a Square

GerdIsenberg — Sun, 24 May 2015 08:02:39 GMT

By Lookup

By Anti-Diagonal Index

Home * Chess * Squares * Color of a Square

The Color of a Square of a 8x8 board may be determined by several approaches. Since the number of files (and ranks) is even, and black and white colors alternate on consecutive ranks (and files), one can not use the simple parity of the combined square index in the 0..63 range. Applications are mostly related square color bounded bishops, for instance to find the right corners in KBNK Endgame.

By Lookup

The obvious approach is a memory lookup of a pre-calculated 64 byte array, containing the color of each square index. Alternatively one may use an In-Register Lookup, using a constant Bitboard representing all dark squares.

0xAA55AA55AA55AA55
 . 1 . 1 . 1 . 1
 1 . 1 . 1 . 1 .
 . 1 . 1 . 1 . 1
 1 . 1 . 1 . 1 .
 . 1 . 1 . 1 . 1
 1 . 1 . 1 . 1 .
 . 1 . 1 . 1 . 1
 1 . 1 . 1 . 1 .

Shifting right this bitboard by square index, and masking off the least significant bit, leaves the square color:

enumColor colorOfSquare (enumSquare square) {
   U64 dark = C64(0xAA55AA55AA55AA55);
   return (dark >> square) & 1;
}

On x86 one may use a shorter 32-bit constant and 32-bit shift, since the 32-bit shift is implicitly modulo 32 ... ^[1]

enumColor colorOfSquare (enumSquare square) {
   return (0xAA55AA55 >> square) & 1; // return (0xAA55AA55 >> (square & 31 )) & 1; 
}

... which also works for 0x88 coordinates, since the In-Register lookup covers one even and odd 16-bit rank.

enumColor colorOfSquare (int x88square) {
   return (0x00AA0055 >> x88square) & 1;
}

By Anti-Diagonal Index

Another approach is based on whether the anti-diagonal index (sum of rank and files) is odd or even. An even index (bit 0 clear) implies a black or dark square, an odd index light or white squares. Since we need to mask off the least significant bit only, we can save masking off the file from square, because upper bits have no influence on bit zero anyway. To be conform with the arbitrary color definition (black == 1 rather than 0), one additional toggleColor, aka xor with '1' is necessary:

enumColor colorOfSquare (enumSquare square) {
   return toggleColor( ((square >> 3) + square) & 1); // +-^
}

Same applies for the diagonal index as well (difference of rank and files), thus one can replace 'plus' by 'minus' or 'exclusive or', as shown in bitwise arithmetic.

A small transformation may save one register ...

enumColor colorOfSquare (enumSquare square) {
   return (( 9 * square + 8 ) >> 3) & 1;
}

... with following x86 assembly in mind:

  lea  eax, [8*eax + eax + 8]
  shr  eax, 3
  and  eax, 1

A boolean condition even saves the shift, but tests bit 3:

bool isDark (enumSquare square) {
   //return (( 9 * square + 8) & 8) != 0;
   return (( 9 * square) & 8) == 0;
}

... with this assembly in mind:

  lea  eax, [8*eax + eax]
  test eax, 8
  jz   isDark

Same color

The same tricks might be applied to determine two squares have the same color or not. If the sum of both anti-diagonal indices is odd, the color is different. Using xor (sq1 ^= sq2) to 'add' ranks and files simultaneously or SWAR-wise without possible overflows saves one instruction.

bool differentColor (enumSquare sq1, enumSquare sq2) {
   sq1 ^= sq2;
   return ( (sq1 >> 3) ^ sq1) & 1;
}

The mentioned lea-transformation saves one register and shift, if one jumps conditionally anyway...

bool differentColor (enumSquare sq1, enumSquare sq2) {
   return (( 9 * (sq1 ^ sq2)) & 8) != 0;
}

... also for the complement expression:

bool sameColor (enumSquare sq1, enumSquare sq2) {
   return (( 9 * (sq1 ^ sq2)) & 8) == 0;
}

Alternatively, if one has a Knight-Distance 64 x 64 array, one may use the least significant bit, since all even Knight-Distances between squares imply same square color.

References

^ Two small in-register-lookups by Gerd Isenberg, CCC, April 23, 2007

What links here?

Page	Date Edited
Bad bishop	Jun 22, 2015
Bishops of Opposite Colors	Aug 22, 2012
Bogol	Jan 2, 2017
Chessboard	May 10, 2017
Color	Mar 12, 2014
Color of a Square	May 24, 2015
Double Attack	Oct 22, 2014
Draw Evaluation	Mar 12, 2018
Intersection Squares	Oct 4, 2014
KBNK Endgame	Nov 26, 2016
Knight-Distance	Oct 20, 2013
Move Generation	Jan 29, 2018
Piece-Lists	Feb 13, 2017
Squares	Feb 15, 2015
Vector Attacks	Dec 15, 2017
Wrong color Bishop and rook pawn	Oct 19, 2017

Up one Level

Discovered Attack

GerdIsenberg — Mon, 08 Nov 2010 13:38:01 GMT

Home * Chess * Tactics * Discovered Attack

A Discovered Attack is a X-ray related chess tactic, revealed when one piece moves out of the way of a sliding piece ray, discovering an attack to squares, opponent pieces or the king, the latter case called a Discovered Check. Discovered attacks can be extremely powerful, as the piece moved can make a threat independently of the piece it reveals.

During move generation or move ordering, one may encourage discovering moves by considering origin squares attacked by an own sliding pieces, as well as the resulting attacking direction.

External Links

What links here?

Page	Date Edited
Battery	Jan 29, 2017
CAPS	Dec 23, 2017
Combination	Oct 25, 2016
Dartmouth CP	Jan 19, 2018
Dictionary	Aug 24, 2017
Discovered Attack	Nov 8, 2010
Discovered Check	Feb 1, 2018
Double Attack	Oct 22, 2014
Double Check	Apr 4, 2013
Move Ordering	Feb 27, 2018
Moves	Feb 19, 2018
Overloading	May 5, 2017
Sliding Pieces	Aug 3, 2017
Tactics	Jan 12, 2018
X-ray	Apr 12, 2017
X-ray Attacks (Bitboards)	Mar 31, 2015
Zwischenzug	Jan 15, 2014

Up one Level

Double Check

GerdIsenberg — Thu, 04 Apr 2013 13:36:31 GMT

See also

External Links

What links here?

Home * Chess * Check * Double Check

A Double Check is a X-ray related chess tactic where two pieces deliver check simultaneously, either most often by one direct check in conjunction with a discovered check, or in exceptional rare cases by two discovered checks after an en passant capture. Only king moves may legal in double check evasion, which is usually considered by a special case move generator even if not strictly legal.

External Links

What links here?

Page	Date Edited
Check	Feb 1, 2018
Checkmate	Apr 13, 2018
Checks and Pinned Pieces (Bitboards)	Aug 14, 2013
Dictionary	Aug 24, 2017
DirGolem	Jun 5, 2016
DiscoCheck	Jun 23, 2017
Discovered Attack	Nov 8, 2010
Discovered Check	Feb 1, 2018
Double Attack	Oct 22, 2014
Double Check	Apr 4, 2013
Lachex	Jan 7, 2016
Legal Move	Feb 16, 2017
Mater	Apr 26, 2016
Move Generation	Jan 29, 2018
Moves	Feb 19, 2018
Spector	Nov 11, 2016
Tactics	Jan 12, 2018

Up one Level

Draw

GerdIsenberg — Sat, 14 Apr 2018 18:34:45 GMT

Home * Chess * Draw

		Draw, the outcome of a chess game when it appears that neither side will win. Draws are codified by various rules of chess including stalemate, threefold repetition, and the fifty-move rule. A draw also occurs when neither player has sufficient material to checkmate the opponent or when no sequence of legal moves can lead to checkmate. Players may further agree to a draw, the side to move may not only claim, but offer a draw, the other side may accept or decline - in computer chess, conform to a protocol and considering game stage, late endgame material configuration, score history and forecast. In official over the board computer chess tournaments such as the World Computer Chess Championship, operator draw agreements require confirmation by the tournament director or arbiter.
Draw "Remis 1990" by Elke Rehder ^[1]

Recognizing Draws

The primary purpose to recognize draws is to direct the chess program to produce drawing moves if alternatives are likely losing, or to avoid draws if ahead and alternative moves most likely win as reflected by the score of the minimax search.

Draw Score

Usually, assuming symmetric evaluation and negamaxed values, positive scores indicate the side to move is ahead, and negative if behind, which defines the value of zero as a natural draw score. However, a score of zero does not necessarily reflect a draw score, but a score of a equal or balanced position. Same is true, if programs apply a contempt factor considering the relative strength of the opponent.

Cray Blitz

Cray Blitz applied a special draw heuristic, not uniformly using zero as draw score, but rather zero plus the ply distance to the root to prefer later draws rather than a draw now. Additionally, the draw score range is disjoint from evaluation scores, which then exclude values around zero by adding or subtracting appropriate offsets if either greater or equal, or less than zero ^[2].

Draw Topics

Publications

David Slate (1984). Interior-node Score Bounds in a Brute-force Chess Program. ICCA Journal, Vol. 7, No. 4, pp. 184-192
Harry Nelson, Robert Hyatt (1988). The Draw Heuristic of Cray Blitz. ICCA Journal, Vol. 11, No. 1, pp. 3-9.
Ernst A. Heinz (1998) Efficient Interior-Node Recognition. ICCA Journal, Vol. 21, No. 3, pp. 156-167
Vladan Vučković, Đorđe Vidanović (2004). A New Approach to Draw Detection by Move Repetition in Computer Chess Programming. CoRR cs.AI/0406038, pdf ^[3]

Forum Posts

1995 ...

50 move rule question by Uri Blass, CCC, April 20, 1999

2000 ...

Shortest Stalemate by Samuel Loyd by Ed Schröder, CCC, March 02, 2001
"Don't trust draw score" <=Is it true? by Teerapong Tovirat, CCC, August 08, 2001
A new(?) technique to recognize draws by Heiner Marxen, CCC, June 01, 2002 » Perpetual Check, Corresponding Squares

2005 ...

Quark 2.35 draw claim bug by Igor Korshunov, Winboard Forum, March 28, 2005 » Quark
Draw scores by Carey, CCC, October 05, 2007 » Draw Score
When and how to return a draw evaluation? by Mathieu Pagé, CCC, August 26, 2008 » Repetitions

2010 ...

Re: question on draw evaluation by Robert Houdart, CCC, June 07, 2010
Wrong draw claim by Naum 4.2 ? by Matthias Gemuh, CCC, January 12, 2011 » Naum, Insufficient Material
Playing better moves in drawish positions (anti-0.00) by Onno Garms, CCC, March 13, 2011 » Onno
final drawscore testing results by Robert Hyatt, CCC, September, 13, 2011
Repetitions/50 moves and TT by Sergei Markoff, CCC, September 13, 2011 » Fifty-move Rule
Texel recipe to fix TT draws scores by Marco Costalba, CCC, June 23, 2012 » Texel
Draw aversion by Don Dailey, OpenChess Forum, December 16, 2012
Value draw by Marek Kwiatkowski, CCC, December 04, 2013

2015 ...

Final Report on Draw Problem in Correspondence Chess by Ciron, Rybka Forum, August 26, 2015 ^[4]
The future of chess and elo ratings by Larry Kaufman, CCC, September 20, 2015 » Match Statistics, Opening Book
Test positions for draw detection by Shawn Chidester, CCC, September 27, 2015 » Test-Positions
Syzygy and draw by repetition by Jon Dart, CCC, July 22, 2016 » Repetitions, Syzygy Bases
Some thoughts about draws by Pio Korinth, CCC, August 03, 2016
The new chess rules (5-fold repetition and 75-move draw) by Lyudmil Antonov, FishCooking, November 29, 2016 » Stockfish, Repetitions
Have engines updated for fide 2014 draw rules? by Norm Pollock, CCC, January 28, 2017
Managing draws in the tree search by Stuart Cracraft, CCC, March 26, 2017
Reporting a draw in UCI by Vince Sempronio, CCC, May 05, 2017 » UCI
Ways to avoid "Draw Death" in Computer Chess by Kai Laskos, CCC, July 25, 2017 » Match Statistics, Playing Strength
Draw scores in TT by Srdja Matovic, CCC, April 14, 2018 » Draw Score, Transposition Table

External Links

References

^ Harry Nelson, Robert Hyatt (1988). The Draw Heuristic of Cray Blitz. ICCA Journal, Vol. 11, No. 1, pp. 3-9.
^ Draw Detection by Move Repetition Procedure -- Comments by Đorđe Vidanović, CCC, August 01, 2004
^ How many points should you get for a draw? by Arno Nickel, ChessBase News, August 20, 2015
^ Final Report on Draw Problem in Correspondence Chess by Ciron, Rybka Forum, August 26, 2015

What links here?

Page	Date Edited
AdaChess	Nov 8, 2016
Blockage Detection	Oct 19, 2017
Carey Bloodworth	Jul 19, 2016
Chess	Jan 21, 2018
Chess Game	Mar 28, 2017
Contempt Factor	Mar 10, 2018
Cray Blitz	Dec 25, 2017
Dabbaba	Oct 21, 2014
Dictionary	Aug 24, 2017
Don Dailey	Dec 7, 2016
Draw	Apr 14, 2018
Draw Evaluation	Mar 12, 2018
Endgame Tablebases	Mar 6, 2018
Fifty-move Rule	Aug 9, 2017
Fortress	Feb 1, 2018
Igor Korshunov	May 16, 2016
Interior Node Recognizer	Mar 12, 2018
Jon Dart	Dec 17, 2017
KBNK Endgame	Nov 26, 2016
KPK	May 12, 2016
Match Statistics	Mar 31, 2018
Material	Mar 31, 2018
Mathieu Pagé	Feb 14, 2018
Matthias Gemuh	Jan 21, 2018
Naum	Nov 23, 2017
Onno	Jul 19, 2013
Onno Garms	Jul 19, 2013
Patzer	Apr 5, 2017
Peasant	May 21, 2015
Psi Chess	Aug 1, 2016
Quark	May 11, 2017
Repetitions	Jan 16, 2018
Retrograde Analysis	Mar 21, 2017
Score	Apr 14, 2018
Search with Random Leaf Values	Apr 23, 2018
Shatranj	Jul 26, 2017
Srdja Matovic	Apr 14, 2018
Stalemate	Feb 21, 2018
Stuart Cracraft	May 19, 2017
Syzygy Bases	Apr 19, 2018
Terminal Node	Nov 17, 2012
Test-Positions	Feb 25, 2018
Transposition Table	Apr 19, 2018
Tucano	Dec 16, 2017
UCI	Mar 4, 2018
Wrong color Bishop and rook pawn	Oct 19, 2017

Up one Level

En passant

GerdIsenberg — Tue, 16 Jan 2018 08:34:29 GMT

Home * Chess * Moves * En passant

En passant (from French: "in passing") ^[1] is a special pawn capture move, which is only possible immediately after an opposing pawn tried passing an advanced pawn on the fifth rank (or fourth for black pawns) by a double pawn push. This double pushed pawn can then be captured the same way, as it would only performed a single push - but only as an immediate reply.

This chess rule makes chess programming a bit harder. First, the target square of the en passant capture is not identical with origin of the captured pawn, opposed to all other captures. Second, the double pawn push, which triggered the immediate possibility of an en passant capture, must be part of the chess position. The information required is whether there was a previous pawn push, and if so, at least the file number of that pawn, considered as en passant target square inside the Forsyth-Edwards Notation (FEN), albeit with the redundant rank (3 or 6) as well.

Legality Test

To prove an en passant capture is actually possible, at least the en passant target square should be under attack of an opponent pawn for pseudo legality. Further, for strict legality, the ep capturing pawn should not be absolutely pinned, which additionally requires a horizontal pin test of both involved pawns, which disappear from the same rank.

8/6bb/8/8/R1pP2k1/4P3/P7/K7 b - d3 after d2-d4

The legality test should be best applied in making of the double pawn push, also considering updating Zobist keys to avoid dissimilarity of otherwise repeated positions if the first occurrence happened after a double pawn push with no en passant capture actually possible ^[2] .

En passant bugs

The implementation of the en passant rule often caused subtle bugs. Almost every chess programmer had various issues with it ^[3] , most notable Louis Kessler with his Program Brute Force. Gerd Isenberg had a special en passant experience with IsiChess at Aegon 1994 in the game versus Henk Arnoldus. IsiChess pushed its white pawn from b2 to b4 "between" the two advanced pawns a4 and c4 from Henk, allowing two possible en passant options. Unfortunately IsiChess only generated one - the "wrong" one (an assembly bug due to jc instead if jnz or that like, otherwise it would not have played it), and was immediately lost after Henk played the "right" one ^[4] ^[5] :

[Event "9th AEGON man-comp"]
[Site "The Hague NED"]
[Date "1994.05.02"]
[Round "4"]
[White "IsiChess"]
[Black "Henk Arnoldus"]
[Result "0-1"]
 
1.e4 e6 2.d4 d5 3.Nd2 Nf6 4.e5 Nfd7 5.Bd3 b6 6.Ngf3 Ba6 7.O-O Bxd3
8.cxd3 Be7 9.Nb3 O-O 10.Bd2 Na6 11.Qe2 Qc8 12.Rac1 Qb7 13.Rc2 c5
14.Rfc1 Rfc8 15.dxc5 bxc5 16.Qe3 Nb4 17.Bxb4 Qxb4 18.Nbd2 a5 19.a3 Qb7
20.Kh1 Ra6 21.d4 c4 22.Qc3 a4 23.b4 axb3 24.Nxb3 Rxa3 25.Nfd2 Rb8
26.Rb1 cxb3 27.Rcb2 Bb4 28.Qc1 Bxd2 29.Rxd2 Ra2 30.Rdb2 Rxb2
31.Qxb2 Qb4 32.f4 g6 33.h3 Qc4 34.Rc1 Qd3 35.f5 Qxf5 0-1

2r3k1/1q1nbppp/r3p3/3pP3/pPpP4/P1Q2N2/2RN1PPP/2R4K b - b3 0 23

Forum Posts

1999

en-passant move generation by Larry Griffiths, CCC, February 06, 1999
Unique nodes, en passant and perfect hashing by Andreas Stabel, CCC, November 25, 1999

2000 ...

annoying en passant x-ray by Georg von Zimmermann, CCC, November 30, 2003

2005 ...

Programmer bug hunt challenge by Ed Schröder, CCC, May 04, 2007 » Portable Game Notation

2010 ...

en passant and hash key calculation by Fred Hamilton, CCC, March 21, 2010
Komodo 3 and a minor bug by Jouni Uski, CCC, September 02, 2011
Re: Causes for inconsistent benchmark signatures by Evert Glebbeek, CCC, March 27, 2013 » Forsyth-Edwards Notation
polyglot en passant square by Marco Belli, CCC, September 12, 2013 » Polyglot
ep and castle rights hashing by Natale Galioto, CCC, September 15, 2013 » Castling rights, Repetitions, Transposition Table
Abundance of castling vs en passant rights by Kirill Kryukov, CCC, April 14, 2014 » Castling
En-passant legality test by tetra, OpenChess Forum, August 07, 2014 » Legal Move

2015 ...

En passant bonus by Lyudmil Tsvetkov, CCC, February 10, 2015 » Pawn Structure
Dynamic EP flag by thevinenator, OpenChess Forum, October 02, 2015
Triple Repitition: Is this considered a repitition or not? by Jayakiran Akurathi, CCC, May 07, 2016 » Repetitions
Enpass + Castling for Zorbist hashes by Andrew Grant, CCC, January 06, 2017 » Castling rights, Zobrist Hashing
3-fold repetition and cutechess-cli by Lars Mathiesen, CCC, January 14, 2018 » Repetitions

External Links

References

^ Earliest Occurrences of Chess Terms by Edward Winter
^ en passant and hash key calculation by Fred Hamilton, CCC, March 21, 2010
^ Chrilly Donninger (1999). Computer machen keine Fehler. CSS 2/99, pdf (German)
^ CSVN Downloads Games Aegon Tournaments
^ Aegon 1994 Round 4 (REPOST) by Dap Hartmann, rgc, May 09, 1994

What links here?

Page	Date Edited
1K ZX Chess	Oct 1, 2015
ACM 1978	Dec 23, 2017
Acornsoft Chess	Dec 11, 2016
Algebraic Chess Notation	Sep 25, 2017
AlphaZero	Feb 10, 2018
Andrew Grant	Jan 13, 2018
Atom Chess	Dec 11, 2016
Atomic Chess	Nov 26, 2016
Board Representation	Dec 11, 2017
BootChess	May 16, 2017
Brute Force (Program)	Sep 7, 2017
Butterfly Boards	Jan 27, 2015
Captures	Oct 1, 2017
Castling	May 5, 2017
Castling rights	Jan 7, 2017
Charly	Jan 10, 2013
Check	Feb 1, 2018
CHEKMO-II	Jan 3, 2018
Chess Position	Sep 10, 2017
ChessLin	May 17, 2017
Color Flipping	May 17, 2017
Copy-Make	May 23, 2017
CTG	Aug 22, 2016
Dabbaba	Oct 21, 2014
David Forthoffer	Apr 25, 2016
Deep Pink	Feb 6, 2017
Dictionary	Aug 24, 2017
DirGolem	Jun 5, 2016
Double Check	Apr 4, 2013
EGA Chess	Nov 30, 2017
En passant	Jan 16, 2018
Encoding Moves	Mar 27, 2016
Engine Testing	Feb 1, 2018
Eval Tuning in Deep Thought	Jun 7, 2016
Evert Glebbeek	Sep 25, 2017
Extended Position Description	Dec 2, 2017
Firstchess	Nov 27, 2014
Forsyth-Edwards Notation	Sep 10, 2017
Galahad	Jan 8, 2015
Gaviota Tablebases	Apr 22, 2018
General Setwise Operations	Feb 25, 2018
Genie	Feb 7, 2016
Georg von Zimmermann	May 29, 2017
Harald Lüßen	Mar 20, 2013
Incremental Updates	Sep 6, 2017
iota	Feb 10, 2016
James Swafford	Jan 1, 2018
Jonathan Warkentin	Jun 29, 2014
Kirill Kryukov	Apr 16, 2014
Lars Rasmussen	Apr 25, 2016
Last Best Reply	Jul 6, 2013
Legal Move	Feb 16, 2017
Little Rook Chess	Sep 1, 2015
Lomonosov Tablebases	May 20, 2016
Lyudmil Tsvetkov	Mar 28, 2018
Make Move	Mar 2, 2016
Marco Belli	Jan 6, 2018
Mark Taylor	Jan 7, 2016
Mate-in-two	Oct 14, 2016
Mini Chess	Jun 7, 2013
Move Generation	Jan 29, 2018
Moves	Feb 19, 2018
MyChess	Dec 25, 2017
Nalimov Tablebases	Dec 23, 2016
Paladin	Jan 29, 2017
Pawn Push	Mar 27, 2010
Pawn Pushes (Bitboards)	Apr 5, 2013
Pawn Structure	Oct 2, 2017
Perft	Sep 26, 2017
Perft Results	Feb 10, 2018
Pieces versus Directions	Oct 6, 2016
Pin	Mar 7, 2017
PolyGlot	Jan 17, 2018
Portable Game Notation	Jan 11, 2018
Pseudo-Legal Move	May 23, 2015
Quad-Bitboards	Jan 30, 2017
Quiet Moves	Mar 4, 2010
Repetitions	Jan 16, 2018
Sito Dekker	Apr 25, 2016
Sneaky Pete	Mar 18, 2016
Squares	Feb 15, 2015
Toledo	Sep 23, 2017
Transposition Table	Apr 19, 2018
Unmake Move	Jun 10, 2017
WMCCC 1996	Sep 15, 2016
Z-Chess	Dec 23, 2017
Zobrist Hashing	Jan 22, 2018

Up one Level

En prise

vincentlejeune — Tue, 11 Oct 2016 15:16:43 GMT

Home * Chess * Tactics * En prise

En prise (from French "can be taken") ^[1] describes a piece or pawn exposed to a material winning capture by the opponent. This is either a hanging piece, a not defended pawn ^[2] , a piece attacked by a lower valuable attacker, or a piece or pawn defended insufficiently. Any least valuable attacker (LVA) would gain a positive score from a static exchange evaluator on the target square, which also applies to a knight defended by a pawn and attacked by bishop and rook, where the majority of attackers and a least valuable attacker of similar value makes the knight en prise.

With pins, overloading, and other tactical motives in mind, whether keeping or putting a piece en prise is a blunder or a sacrifice is a matter of search, the latter may require some depth left to differentiate.

External Links

En prise - Glossary of chess from Wikipedia
en prise - Wiktionary
Earliest Occurrences of Chess Terms by Edward Winter
En Prise - Chess Basics
En prise from ChessBase News, April 13, 2012

References

^ Earliest Occurrences of Chess Terms by Edward Winter
^ The ambiguous term hanging pawns refers a duo of open and half-isolated pawns

What links here?

Page	Date Edited
CAPS	Dec 23, 2017
Captures	Oct 1, 2017
Deflection	May 21, 2011
Delicate Brute	Jun 7, 2016
Dictionary	Aug 24, 2017
En prise	Oct 11, 2016
Golch	Dec 7, 2017
Hanging pawns	Aug 5, 2015
Hanging Piece	Jan 14, 2017
Loose Piece	Jan 10, 2015
Mac Hack	Apr 20, 2018
Machiavelli	Jun 2, 2015
Mobility	Jan 17, 2018
Ostrich	Dec 28, 2017
Overloading	May 5, 2017
Pieces	Feb 19, 2018
Pin	Mar 7, 2017
Point Value	Mar 31, 2018
Querg	Dec 11, 2013
Sinobyl	Jul 3, 2014
Skewer	Oct 22, 2014
SOMA	Mar 25, 2015
Square Control	Sep 15, 2016
Tactics	Jan 12, 2018
Trajectory	Jan 3, 2015
Transposition	Jun 8, 2015
Undermining	Jun 10, 2012

Up one Level

Files

GerdIsenberg — Sun, 22 Nov 2015 21:49:15 GMT

Home * Chess * Files

For disambiguation see also Computer file

Files are the eight vertical lines or columns of a Chessboard, labeled from 'A' to 'H', or 'a' to 'h'. Each file contains eight vertically arranged Squares of alternating white and black, or light and dark Color. In a descriptive notation, files are also nominated by the Pieces from their initial position (similar to Pawns), like Rook-Files (A- and H-File), Knight-Files (B- and G-File), Bishop-Files (C- and F-File), and Queen-File (D-File) and King-File (E-File), also called Center Files.

Square Mapping Notes

Whether the square difference of neighbored squares on a rank or file is either 1 or 8, depends on the square mapping. We further rely on little-endian rank-file mapping, which keeps consecutive squares of a rank as neighbored elements in Memory (or register).

Square Difference

Within a 0..63 square index range and the mentioned square mapping (a1 = 0), the difference of two neighbored squares on a File is eight.

Enumeration

As mentioned, on a Chessboard the eight files are labeled from 'A' to 'H'. To make them zero based indices as appropriate for C like programming languages, we enumerate files from 0 to 7. Little-endian file-mapping (as used here) assigns the A-File to index zero. Three bits are required to enumerate from 0 to 7.

A little-endian file-mapping enumeration in C++ might look like this:

enum enumFile {
  efAFile = 0,
  efBFile = 1,
  efCFile = 2,
  efDFile = 3,
  efEFile = 4,
  efFFile = 5,
  efGFile = 6,
  efHFile = 7,
};

File from Square

Rank-File mapping of squares keeps the file as the three lower bits of a Square index.

file = square & 7; // modulo 8

File-Distance

The file-distance is the absolute difference between two files (their 0-7 indices). The maximum file-distance is 7.

fileDistance = abs (file1 - file2);
fileDistance = abs (file2 - file1);

What links here?

Page	Date Edited
0x88	Nov 28, 2016
10x12 Board	Feb 19, 2018
8x8 Board	Aug 29, 2017
Abyss	Aug 5, 2017
Algebraic Chess Notation	Sep 25, 2017
Amyan	Dec 10, 2013
Anti-Diagonals	Sep 2, 2012
Array	Dec 1, 2016
Battery	Jan 29, 2017
Big-endian	Jan 25, 2015
Byte	Apr 5, 2013
CC Sapiens	Oct 29, 2014
Center	Jun 21, 2016
Chess	Jan 21, 2018
Chess 0.5	Nov 20, 2016
Chess Position	Sep 10, 2017
Chessboard	May 10, 2017
ChessV	Jan 21, 2018
Chinese Chess	Jan 16, 2018
Chinese Chess Board Representation	Jul 25, 2017
Color of a Square	May 24, 2015
Congruent Modulo Bitboards	Jun 26, 2013
Delfi	Jan 7, 2016
DGT Board	Feb 21, 2018
Diagonal Mirroring	Jun 29, 2013
Diagonals	Jan 16, 2013
Dictionary	Aug 24, 2017
Direction	Oct 6, 2016
Distance	Sep 25, 2015
Doubled Pawn	Mar 27, 2017
Efficient Generation of Sliding Piece Attacks	Nov 5, 2016
En passant	Jan 16, 2018
Entering Moves	Sep 7, 2017
Files	Nov 22, 2015
First Rank Attacks	Aug 28, 2010
Flipping Mirroring and Rotating	Oct 14, 2016
Gk	Oct 9, 2017
Glaurung	Mar 14, 2017
Half-open file	Mar 11, 2014
Horizontal Mirroring	Jun 29, 2013
Hyperbola Quintessence	Mar 25, 2017
Influence Quantity of Pieces	Jul 21, 2017
Intersection Squares	Oct 4, 2014
Isolated Pawn	Nov 18, 2012
Isolated Pawns (Bitboards)	Nov 18, 2012
KBNK Endgame	Nov 26, 2016
Kindergarten Bitboards	Aug 1, 2017
King	Feb 26, 2013
Knight-Distance	Oct 20, 2013
Konrad Zuse	Apr 30, 2015
KRK	Nov 26, 2016
Kurt	Apr 20, 2014
Little-endian	Jan 25, 2015
MadChess	Jul 4, 2017
Mailbox	Apr 14, 2018
Manhattan-Distance	May 19, 2014
Mate at a Glance	Sep 24, 2014
Mephisto Europa	Jun 23, 2017
Mop-up Evaluation	Nov 26, 2016
Nibble	Jan 25, 2015
NoraGrace	Nov 23, 2014
Novag Forte	Aug 3, 2013
Novag Micro Chess	Jan 16, 2013
Obstruction Difference	May 27, 2016
Occupancy of any Line	Sep 16, 2016
OliThink	May 19, 2017
Opposition	Dec 2, 2014
Paul Wiereyn	Jun 4, 2015
PawnKing	Sep 5, 2014
Pawns and Files (Bitboards)	Jan 16, 2013
Promotion Square	Aug 15, 2011
Ranks	Dec 15, 2008
Rays	Oct 20, 2016
Rook on Open File	Apr 24, 2017
Rotated Bitboards	Mar 7, 2017
Rule of the Square	Sep 6, 2014
Ryan Mack	Jan 18, 2011
SBAMG	Dec 4, 2016
Scidlet	May 31, 2014
Senpai	Nov 10, 2017
SIMD techniques	Nov 26, 2017
Sliding Pieces	Aug 3, 2017
Square Mapping Considerations	Feb 28, 2018
Squares	Feb 15, 2015
SSSE3	Aug 8, 2017
Subtracting a Rook from a Blocking Piece	Dec 2, 2016
User Interface	Feb 21, 2018
Vajolet	Jan 25, 2018
Vector Attacks	Dec 15, 2017
Vlad Petric	Oct 25, 2013
Wing	Oct 26, 2017
Winglet	Apr 26, 2015
Woodpecker	Nov 22, 2015
Zobrist Hashing	Jan 22, 2018

Up one Level

Wikispaces : chessprogramming - items matching description

Algebraic Chess Notation

Table of Contents

Pure coordinate notation

XBoard

UCI

Output Samples

ICCF numeric notation

Smith notation

Long Algebraic Notation (LAN)

Standard Algebraic Notation (SAN)

Ambiguities

Captures

En passant

Pawn promotion

Castling

Converting Moves

XBoard 2

Figurine Algebraic Notation (FAN)

Vector Graphics

LaTeX

Reading Chess

See also

Publications

Forum Posts

External Links

References

What links here?

Captures

Table of Contents

Capture Generation

Six times Take Five

See also

Forum Posts

External Links

What links here?

Castling

Table of Contents

Rules

Chess960

Shogi

See also

Forum Posts

1982

2000 ...

2010 ...

External Links

References

What links here?

Castling rights

Table of Contents

See also

Forum Posts

External Links

What links here?

Check

Table of Contents

Kind of Checks

Single Check

Double Check

In Check Detection

By last Move

Attack Tables

On the Fly

Getting out of check

Double Check

Single Check

Perpetual Check

See also

Publications

Forum Posts

1997 ...

2000 ...

2005 ...

2010 ...

2015 ...

External Links

References

What links here?

Checkmate