Slow Chess

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Slow Chess, (SlowChess, Slow Chess Blitz) a WinBoard and UCI compliant engine chess engine by Jonathan Kreuzer, which also comes with an own GUI. Older versions, Slow Chess 2.82a, and Slow Chess 2.96, not related to the more recent Slow Chess Blitz, are open source. Slow Chess is written in C++ with a little inline assembly, and was first released in July 2003. Slow Chess played the ACCA 2008 operated by Swaminathan Natarajan. After a 14-year hiatus, a new version of Slow Chess Blitz was released in September 2019.

=Screenshot= Slow Chess, Windows GUI

=Description= Slow Chess 2.96's internal board is represented by a 10x12 board in conjunction with piece-lists. The search applies PVS alpha-beta with transposition table and null move pruning inside an iterative deepening framework with aspiration windows. Move ordering is enhanced by IID, MVV-LVA, history heuristic, and killer heuristic. Despite direct recursion, it does not negamax, but conditional min or max. Checks, recaptures, pawn moves to the 7th rank, single replies and mate threatening moves are extended by fractions of a ply. Evaluation considers material and piece-square tables with an lazy exit if outside bounds, and otherwise cashes pawn structure stuff in a pawn hash table, evaluates king safety along with king piece tropism, and various terms for pieces such as trapped bishops. All evaluation scores greater than 4 or less than -4 are quantized and have its two least significant bits clear to make the scores multiples of ±4.

=Selected Games= ACCA 2008, round 2, Slow Chess - Amateur [Event "ACCA 2008"] [Site "Internet Chess Club"] [Date "2008.11.08"] [Round "2"] [White "Slow Chess"] [Black "Amateur"] [Result "1-0"]

1.d4 Nf6 2.c4 e6 3.g3 d5 4.Nf3 dxc4 5.Qa4+ Bd7 6.Qxc4 Bc6 7.Bg2 Bd5 8.Qd3 Be4 9.Qd1 Nc6 10.O-O Nb4 11.Nc3 Bc2 12.Qd2 Ne4 13.Qe1 Nd5 14.Ne5 Bb4 15.Bd2 Bxc3 16.bxc3 f6 17.Rc1 Nxd2 18.Qxd2 Bf5 19.Nc4 Bg4 20.Na5 b5 21.c4 bxc4 22.Rxc4 O-O 23.Rfc1 Bh5 24.R4c5 f5 25.Nc6 Qf6 26.Bxd5 exd5 27.Ne5 f4 28.Nd7 Qe6 29.Nxf8 Rxf8 30.f3 fxg3 31.hxg3 Qh3 32.Qe1 Qe6 33.R5xc7 Re8 34.Qd2 h6 35.R1c6 Qxe2 36.Qxe2 Rxe2 37.Rxa7 Bxf3 38.Rg6 Be4 39.Rgxg7+ Kh8 40.Rge7 Rg2+ 41.Kf1 Rxg3 42.Ra8+ Rg8 43.Rxg8+ Kxg8 44.Rxe4 dxe4 45.a4 Kf7 46.a5 1-0

=Forum Posts=

2004

 * My Pick for Strongest Amateur Program ("SlowChess!) Commercial? by Nolan Denson, CCC, January 30, 2004
 * SlowChess Blitz rocks !! by Axel Schumacher, CCC, November 22, 2004
 * SlowChess Blitz 2004 by Karl-Heinz Söntges, CCC, November 23, 2004
 * More great SlowChess Blitz results! by Axel Schumacher, CCC, November 24, 2004
 * CM9000 Default v SlowChess G-10 20-game match by John Merlino, CCC, November 25, 2004

2005 ...

 * SlowChess Blitz WV is stunning is test suites! by Jouni Uski, CCC, October 24, 2005
 * Slowchess 2.96 Windows 64-bit build available by Jim Ablett, CCC, December 19, 2007
 * SlowChess in ACCA by Swaminathan, CCC, November 11, 2008 » ACCA 2008

2010 ...

 * SlowChess 2.96 LS (Limit Strength) by Alexander Schmidt, CCC, November 18, 2012
 * I Am Lost With This SlowChess 2.960-Makes No Sense by George Speight, CCC, April 08, 2013
 * Slow Chess by Fernando Villegas, CCC, September 05, 2015
 * Slow Chess Blitz Classic by Jonathan Kreuzer, CCC, September 04, 2019

2020 ...

 * SlowChess Blitz Classic 2.0 by Jonathan Kreuzer, CCC, March 20, 2020
 * Just found a 55 elo bug in SlowChess 2.1 by Jonathan Kreuzer, CCC, June 01, 2020
 * Learning/Tuning in SlowChess Blitz Classic by Jonathan Kreuzer, CCC, June 15, 2020 » Automated Tuning

=External Links=
 * Slow Chess Blitz, a free chess program
 * Programming Details - Slow Chess | Extensions Used, Detailed Description
 * Automatic Tuning & Learning for Slow Chess Blitz Classic by by Jonathan Kreuzer » Automated Tuning
 * History of Slow Chess
 * Slow Chess Blitz in CCRL 40/15

=References= Up one level