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Nov 13, 2017
**[[Home]] * [[Engines]] * RedQueen**
|| [[image:193px-Tenniel_red_queen_with_alice.jpg link="https://en.wikipedia.org/wiki/File:Tenniel_red_queen_with_alice.jpg"]] ||~ || **RedQueen**,
an [[UCI]] compliant [[Open Source Engines|open source chess engine]] under the [[Free Software Foundation#GPL|GNU General Public License]], written in [[Cpp|C++]] by [[Ben-Hur Carlos Vieira Langoni Junior]]. Using minimal library dependencies as possible, it could easily ported to various [[Software|operating systems]] such as [[Windows]], [[Linux]], [[Mac OS]], and [[Android]]. The name RedQueen was inspired by the [[https://en.wikipedia.org/wiki/Red_Queen_%28Through_the_Looking-Glass%29|Red Queen character]] in [[Various Classifications#Carroll|Lewis Carroll's]] [[https://en.wikipedia.org/wiki/Through_the_Looking-Glass|Through the Looking-Glass]] novel <ref>[[http://redqueenchess.sourceforge.net/|RedQueen | Chess Engine]]</ref> . ||
|| The [[RedQueen|Red Queen]] lecturing [[Alice]] <ref>Illustration by [[Arts#Tenniel|John Tenniel]] of the [[RedQueen|Red Queen]] lecturing [[Alice]] for [[Various Classifications#Carroll|Lewis Carroll's]] "[[https://en.wikipedia.org/wiki/Through_the_Looking-Glass|Through The Looking Glass]]", 1871, [[https://en.wikipedia.org/wiki/Red_Queen_%28Through_the_Looking-Glass%29|Red Queen (Through the Looking-Glass) - Wikipedia]]</ref> ||~ ||^ ||
[[toc]]
=Description=
==Bitboards==
RedQueen is a [[Bitboards|bitboard]] engine and uses [[Pradu Kannan|Pradu Kannan's]] [[Magic Bitboards|magic bitboards]] <ref>[[http://sourceforge.net/projects/redqueenchess/|redqueen-1.1.2-windows.zip download]], magicmoves.h, magicmoves.cpp</ref> to determine [[Sliding Piece Attacks|sliding piece attacks]]. [[BitScan|BitScans]] are either implemented in [[Assembly#InlineAssembly|inline assembly]] for [[x86-64]] [[BitScan#bsfbsr|processor instructions]], or with [[BitScan#DeBruijnMultiplation|De Bruijn multiplication]] and [[BitScan#DoubleConversionBSR|double conversion]] for forward and reverse scans respectively [[#BitScan]] <ref>[[http://sourceforge.net/projects/redqueenchess/|redqueen-1.1.2-windows.zip download]], bitboard.h</ref>:
[[code format="cpp"]]
const uint64_t debruijn64 = 0x07EDD5E59A4E28C2ULL;
const uint32_t index64[64] = {
63, 0, 58, 1, 59, 47, 53, 2,
60, 39, 48, 27, 54, 33, 42, 3,
61, 51, 37, 40, 49, 18, 28, 20,
55, 30, 34, 11, 43, 14, 22, 4,
62, 57, 46, 52, 38, 26, 32, 41,
50, 36, 17, 19, 29, 10, 13, 21,
56, 45, 25, 31, 35, 16, 9, 12,
44, 24, 15, 8, 23, 7, 6, 5
};
inline int bitScanForward(int* const index, const uint64_t mask) {
#if defined(__LP64__)
uint64_t ret;
asm ("bsfq %[mask], %[ret]" : [ret] "=r" (ret) :[mask] "mr" (mask));
*index = int(ret);
#else
*index = int(index64[((mask & -mask) * debruijn64) >> 58]);
#endif
return mask?1:0;
}
inline int bitScanReverse(int* const index, const uint64_t mask) {
#if defined(__LP64__)
uint64_t ret;
asm ("bsrq %[mask], %[ret]" :[ret] "=r" (ret) :[mask] "mr" (mask));
*index = (unsigned int)ret;
#else
union {
double d;
struct {
unsigned int mantissal : 32;
unsigned int mantissah : 20;
unsigned int exponent : 11;
unsigned int sign : 1;
};
} ud;
ud.d = (double)(mask & ~(mask >> 32));
*index = ud.exponent - 1023;
#endif
return mask?1:0;
}
[[code]]
Similar holds for [[Population Count|population count]] with [[SSE4]] instruction if available versus [[Population Count#SWARPopcount|SWAR-popcount]], also using an optimized version for populations below 16, borrowed from [[Stockfish]].
==Search==
RedQueen applies a [[Parallel Search|parallel search]] considering the [[Young Brothers Wait Concept]] using a pool of [[Thread|threads]] where a master spawns idle threads. The [[Search|search]] is [[Principal Variation Search|PVS]] [[Alpha-Beta|alpha-beta]] with the [[Shared Hash Table|shared]] [[Transposition Table|transposition table]] inside an [[Iterative Deepening|iterative deepening]] framework with [[Aspiration Windows|aspiration windows]]. [[Selectivity]] is applied by [[Check Extensions|check]] and [[PV Extensions|PV extensions]], [[Null Move Pruning#AdaptiveNullMovePruning|adaptive nullmove pruning]], [[Razoring|razoring]], [[Futility Pruning|futility pruning]], [[Reductions|reductions]] at [[Node Types#PV|PV-]] and more aggressively at none PV-nodes. The [[SEE - The Swap Algorithm|SEE swap algorithm]] is used to prune bad [[Captures|captures]] in [[Quiescence Search|quiescence search]], as well in [[Move Ordering|move ordering]], which is further improved by the obligatory [[Killer Heuristic|killer-]] and [[History Heuristic|history heuristics]].
==Evaluation==
The [[Evaluation|evaluation]] might be [[Lazy Evaluation|lazy]] and otherwise considers [[Tactics|tactical]] and positional features as well as [[Material|material imbalances]] along with a [[Pawn Hash Table|pawn structure cache]] and a [[Tapered Eval|tapered eval]] interpolating [[Middlegame|middlegame]] and [[Endgame|endgame]] [[Score|scores]] with [[Passed Pawn|passed pawn]] and [[King Safety|king safety]] and most dominant terms beside material.
=Tournament Play=
Over the board, RedQueen played the [[ICT 2010]], [[DOCCC 2010]], [[ICT 2011]], [[ICT 2012]], and [[PT 52]] [[CSVN]] tournaments in [[https://en.wikipedia.org/wiki/Leiden|Leiden]], online the [[ACCA 2010]], [[ACCA 2011]], [[CCT13]], [[CCT14]], and the [[WCRCC 2011]].
=Selected Games=
[[ACCA 2011]], round 2, [[RedQueen]] - [[Crafty]] <ref>[[http://www.talkchess.com/forum/viewtopic.php?t=41067|2011 6ht annual ACCA games (RedQueen's games)]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], November 13, 2011</ref>
[[code]]
[Event "ACCA 2011"]
[Site "HGM's server"]
[Date "2011.11.12"]
[Round "2"]
[White "RedQueen"]
[Black "Crafty"]
[Result "1/2-1/2"]
1.c4 e6 2.Nf3 d5 3.d4 Nf6 4.Nc3 Be7 5.Bf4 O-O 6.e3 Nbd7 7.c5 Nh5 8.Bd3 Nxf4
9.exf4 c6 10.Qc2 g6 11.h4 Nf6 12.a3 b6 13.b4 Qc7 14.g3 a5 15.Na4 b5 16.Nb6
Ra7 17.O-O axb4 18.axb4 Rxa1 19.Rxa1 Bb7 20.Qe2 Nd7 21.Nxd7 Qxd7 22.Ne5 Qc7
23.h5 Bf6 24.Qg4 Re8 25.Ra7 Kf8 26.hxg6 hxg6 27.Nxf7 Qxf7 28.Bxg6 Qg7 29.Rxb7
Qxb7 30.Bxe8 Kxe8 31.Qxe6+ Be7 32.f5 Qd7 33.Qg8+ Bf8 34.Qg6+ Kd8 35.Qf6+ Be7
36.Qh8+ Qe8 37.Qe5 Kd7 38.Qe6+ Kd8 39.Qe5 Kd7 40.Qe6+ Kd8 41.Qe5 1/2-1/2
[[code]]
=See also=
* [[Various Classifications#ChessPieces|Chess Pieces]]
* [[Various Classifications#Comics|Comics]]
* [[Various Classifications#Carroll|Lewis Carroll characters]]
* [[Queen (engine)]]
=Forum Posts=
==2010==
* [[http://www.talkchess.com/forum/viewtopic.php?t=35846|RedQueen 0.6]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], August 21, 2010
* [[http://www.talkchess.com/forum/viewtopic.php?t=36417|Redqueen v0.7]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], October 18, 2010
* [[http://www.talkchess.com/forum/viewtopic.php?t=36630|Redqueen v0.7.5 (ACCA 2010)]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], November 08, 2010 » [[ACCA 2010]]
* [[http://www.talkchess.com/forum/viewtopic.php?t=36891|Redqueen v0.8]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], December 01, 2010
* [[http://www.talkchess.com/forum/viewtopic.php?t=36967|Test position for average engines]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], December 06, 2010 » [[DOCCC 2010]], [[Fridolin]]
==2011==
* [[http://www.talkchess.com/forum/viewtopic.php?t=37884|Redqueen v0.9 release]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], January 31, 2011
* [[http://www.talkchess.com/forum/viewtopic.php?t=38015|Redqueen v0.9.1 release]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], February 10, 2011
* [[http://www.talkchess.com/forum/viewtopic.php?t=38149|Redqueen v0.9.5 release]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], February 21, 2011
* [[http://www.talkchess.com/forum/viewtopic.php?t=38638|RedQueen for Android]] by [[Aart Bik]], [[CCC]], April 03, 2011
* [[http://www.talkchess.com/forum/viewtopic.php?t=38888|RedQueen v0.9.8 release]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], April 27, 2011
* [[http://www.talkchess.com/forum/viewtopic.php?t=39819|2011 Fifth Annual ACCA WCRCC: RedQueen games]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], July 23, 2011 » [[WCRCC 2011]]
* [[http://www.talkchess.com/forum/viewtopic.php?t=40265|RedQueen 1.0 beta release]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], September 04, 2011
* [[http://www.talkchess.com/forum/viewtopic.php?t=41067|2011 6ht annual ACCA games (RedQueen's games)]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], November 13, 2011 » [[ACCA 2011]]
==2012 ...==
* [[http://www.talkchess.com/forum/viewtopic.php?t=42884|RedQueen 1.1 released]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], March 15, 2012
* [[http://www.talkchess.com/forum/viewtopic.php?t=42892|RedQueen 1.1.1 (bugfix release)]] by [[Ben-Hur Carlos Vieira Langoni Junior|Ben-Hur Carlos Langoni]], [[CCC]], March 15, 2012
* [[http://www.talkchess.com/forum/viewtopic.php?t=42896|RedQueen 1.1.1 on Mac OS X]] by [[Robert Purves]], [[CCC]], March 16, 2012
* [[http://www.talkchess.com/forum/viewtopic.php?t=43021|Redqueen 1.1.1 64-bit - Is this a bug?]] by [[Gabor Szots]], [[CCC]], March 26, 2012
=External Links=
==Chess Engine==
* [[http://sourceforge.net/projects/redqueenchess/|RedQueen Chess Engine website]]
* [[http://redqueenchess.sourceforge.net/|RedQueen | Chess Engine]]
* [[http://www.computerchess.org.uk/ccrl/404/cgi/engine_details.cgi?print=Details+%28text%29&eng=RedQueen%201.1.2%2064-bit%202CPU|RedQueen 1.1.2 64-bit 2CPU]] in [[CCRL|CCRL 40/4]]
* [[http://computerchess.org.uk/ccrl/4040/cgi/engine_details.cgi?print=Details+%28text%29&eng=RedQueen%201.0.0%2064-bit|RedQueen 1.0.0 64-bit]] in [[CCRL|CCRL 40/40]]
==Misc==
* [[https://en.wikipedia.org/wiki/Red_Queen|Red Queen (disambiguation) from Wikipedia]]
* [[https://en.wikipedia.org/wiki/Red_Queen_%28Through_the_Looking-Glass%29|Red Queen (Through the Looking-Glass) - Wikipedia]]
> [[https://en.wikipedia.org/wiki/Red_Queen%27s_race|Red Queen's race from Wikipedia]]
* [[https://en.wikipedia.org/wiki/The_Red_Queen%27s_Race|The Red Queen's Race from Wikipedia]] ([[https://en.wikipedia.org/wiki/Isaac_Asimov|Isaac Asimov]])
* [[https://en.wikipedia.org/wiki/Red_Queen_hypothesis|Red Queen hypothesis from Wikipedia]]
* [[https://en.wikipedia.org/wiki/Red_Queen_%28comics%29|Red Queen (comics) from Wikipedia]]
* [[https://en.wikipedia.org/wiki/The_Red_Queen:_Sex_and_the_Evolution_of_Human_Nature|The Red Queen: Sex and the Evolution of Human Nature - Wikipedia]]
* [[https://en.wikipedia.org/wiki/Gryphon_%28band%29|Gryphon]] - [[https://en.wikipedia.org/wiki/Red_Queen_to_Gryphon_Three|Red Queen to Gryphon Three]], 1974, [[https://en.wikipedia.org/wiki/YouTube|YouTube]] Video
> [[media type="youtube" key="INn8BO9iMCc"]]
=References=
<references />
=What links here?=
[[include page="RedQueen" component="backlinks" limit="40" ]]
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