Sjaak+(Glebbeek)

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an open source engine under the GNU General Public Licence written in C by Evert Glebbeek as younger sibling of Jazz, but able to play chess variants on various board sizes compliant to the Chess Engine Communication Protocol. Sjaak was first released in January 2011, not to confused with Ronald de Man's older private engine with the same name. The further extended **SjaakII**, released in early 2015, supports even more variants and protocols, and runs best under XBoard/WinBoard, version 4.8 (or better).
 * Sjaak** ,

=Variants= > Indian Grand Chess, or possibly Turkish Grand Chess. On a 10x10 with four extra pieces.
 * Amazon Chess, where the queen moves as an amazon (needs to be played as variant "fairy" in XBoard).
 * Berolina Chess, where pawns move one square diagonal and capture straight ahead.
 * Burmese Chess, working but not tested fully.
 * Capablanca Chess, a variant played on a 10x8 board with two extra pieces.
 * Capablanca Random Chess
 * Chess960 (Fischer Random Chess)
 * Chinese Chess
 * Courier Chess, a medieval variant played on a 12x8 board.
 * Crazyhouse
 * Gothic Chess, the same as Capablanca Chess but with a different starting position.
 * Grand Chess, on a 10x10 board.
 * Knightmate, where the king moves as a knight and the knights move as a king.
 * Makruk, the Thai version of Chess.
 * Normal chess
 * Pocket Knight, like normal chess, but players have an extra knight they can drop on the board.
 * Shatranj, a historic precursor of modern chess.
 * Shogi
 * Spartan Chess, where black and white play with different armies and black has two kings
 * The Maharaja and the Sepoys, where white has only one piece (the Maharaja) (needs to be played as variant "fairy" in XBoard).

=Description=

Board Representation
Despite boards exceeding 64 squares, like 10x8, 12x8, and 10x10, Sjaak is a native bitboard engine, utilizing either GCC's __int128 extenstion on 64-bit platforms such as x86-64 or 128 bit vectors of integers on 32-bit platforms, the latter supporting SSE2 if available. Sjaak applies Kindergarten Bitboards to determine sliding piece attacks.

Search
Sjaak uses a fail-soft alpha-beta principal variation search with quiescence, null move pruning, late move reductions and check extensions inside an iterative deepening framework with transposition table. Move ordering considers the killer, countermove and history heuristics. A modified version of a SEE routine from Jazz is used to evaluate captures.

Evaluation
Sjaak's static evaluation takes material balance, static piece-square tables derived from heuristics based on how pieces move, mobility and king safety into account, the latter only in chess variants with one king per side.

=Namesake=
 * Sjaak (TrojanKnight) by Ronald de Man

=See also=
 * Given Name
 * Jazz
 * Leonidas
 * Sjakk

=Forum Posts=

2010 ...

 * [|New Spartan-Chess engine: Sjaak] by Harm Geert Muller, CCC, January 20, 2011
 * [|Sjaak 263] by Evert Glebbeek, CCC, October 31, 2011
 * [|Xiangqi chase algorithm] by Evert Glebbeek, CCC, November 16, 2011 » Chinese Chess
 * [|Sjaak 342 - new variants] by Evert Glebbeek, CCC, November 16, 2011
 * [|Sjaak 437] by Evert Glebbeek, CCC, December 11, 2011
 * [|Sjaak 468 JA available] by Jim Ablett, CCC, January 23, 2012
 * [|Sjaak updated (revision 506)] by Evert Glebbeek, CCC, February 01, 2013
 * [|Shogi] by Evert Glebbeek, CCC, October 20, 2014 » Shogi
 * [|Xiangqi chase - again] by Evert Glebbeek, CCC, November 06, 2014 » Chinese Chess
 * [|Sjaak II - beta release!] by Evert Glebbeek, CCC, November 19, 2014

2015 ...
> [|SjaakII 1.2.0 is out!] by Evert Glebbeek, CCC, January 08, 2016 > [|SjaakII 1.2.1 is out!] by Evert Glebbeek, CCC, January 10, 2016
 * [|SjaakII 1.0 RC1] by Evert Glebbeek, CCC, January 29, 2015
 * [|SjaakII 1.0.0] by Evert Glebbeek, CCC, March 18, 2015
 * 2016**
 * [|SjaakII 1.2 RC1] by Evert Glebbeek, CCC, January 02, 2016
 * [|Sjaak II question] by Harm Geert Muller CCC, March 16, 2016
 * [|SjaakII 1.3.0 (the happy easter edition)] by Evert Glebbeek, CCC, March 26, 2016
 * [|Question about Sjaak] by Michel Van den Bergh, CCC, April 01, 2016
 * [|Sjaak II, Wa Shogi and XBoard 4.9] by Harm Geert Muller, CCC, April 25, 2016 » Shogi, XBoard
 * [|SjaakII 1.3.1] by Evert Glebbeek, CCC, July 05, 2016
 * [|SjaakII 1.4.0] by Evert Glebbeek, CCC, November 27, 2016
 * [|Sjaak II 1.4.1 and Shogi] by Harm Geert Muller, CCC, December 14, 2016 » Shogi
 * 2017**
 * [|I hate this hobby...] by Evert Glebbeek, CCC, January 20, 2017 » Shogi

=External Links=

Chess Engine

 * [|Chess (Jazz & Sjaak) home]
 * [|Chess (Jazz & Sjaak) downloads]
 * [|Sjaak 399] in CCRL 40/4

Misc
> media type="youtube" key="4JgdjhEIh4w"
 * [|Sjaak from Wikipedia]
 * [|Sjaak from Wikipedia.nl] (Dutch)
 * Willem Breuker, Pierre Courbois, [|Victor Kaihatu] - Wonderful Girl of 17 Springs (1966), [|YouTube] Video

=References= =What links here?= include page="Sjaak (Glebbeek)" component="backlinks" limit="40"
 * Up one level**