Critter

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Critter, an UCI compliant chess engine by Richard Vida, executables freely available for personal use to run under Windows, Linux, Android and Mac OS. Starting in late 2008, Critter was first written in Object Pascal compiled with Delphi, now available as open source engine, and was ported to C / C++ in 2009. It consistently evolved through various board representations from 0x88 to bitboards, as acknowledged by Richard Vida, also incorporating ideas from strong open source programs like Ippolit, to a world class engine which achieved top five of most engine rating lists. In 2012, Critter had its over the board debut at the ICT 2012, where it became strong runner-up behind the Rybka cluster.

=Description= Critter applies a principal variation search with aspiration windows, null move pruning and other state of the art forward pruning, reduction and extension techniques, such as the Botvinnik-Markoff extensions. It can search in parallel with up to eight threads, supports Gaviota tablebases , and is able to play Chess960. Critter features a tapered eval with a score pair class and overloaded operators, and blockage detection in late endgames.

=Selected Games= ICT 2012, round 7, Rybka - Critter [Event "ICT12"] [Site "Leiden"] [Date "2012.05.13"] [Round "7"] [White "Rybka"] [Black "Critter"] [Result "1/2-1/2"]

1.d4 d5 2.c4 e6 3.Nf3 c6 4.e3 Bd6 5.b3 f5 6.Bd3 Nf6 7.O-O Qe7 8.Bb2 O-O 9.Qc1 b6 10.Ba3 Bb7 11.Bxd6 Qxd6 12.Nc3 dxc4 13.Bxc4 Nbd7 14.Re1 b5 15.Bd3 b4 16.Na4 c5 17.Nxc5 Bxf3 18.gxf3 Rfc8 19.Bc4 Nxc5 20.dxc5 Rxc5 21.a3 bxa3 22.Qxa3 Nd5 23.Red1 Qc7 24.Kg2 Rd8 25.Bxd5 Rdxd5 26.Qa4 Qe7 27.Rxd5 Rxd5 28.Qxa7 Qxa7 29.Rxa7 Rb5 30.Re7 Rb6 31.Kg3 Kf8 32.Rd7 Rxb3 33.Kf4 Rb5 34.h4 h6 35.Kg3 Rb8 36.h5 Re8 37.Rb7 Re7 38.Rb5 Kf7 39.e4 Kf6 40.exf5 exf5 41.Kf4 Re2 42.Rxf5+ Ke6 43.Rb5 Rxf2 44.Rb6+ Kf7 45.Rb7+ Kf6 1/2-1/2

=Publications=
 * Arno Nickel (2012). Die schöne neue Welt der Schachengines. SCHACH 2,3,5,6 2012, pdf (German)

=Forum Posts=

2009

 * Critter 0.34 : 2146 by Patrick Buchmann, CCC, April 18, 2009
 * Critter 0.38 : 2330 by Patrick Buchmann, CCC, May 22, 2009
 * Critter 0.40 released by Richard Vida, CCC, July 26, 2009
 * Critter 0.40 : 2471 by Patrick Buchmann, CCC, August 01, 2009
 * Critter: Pascal vs C by Richard Vida, CCC, August 27, 2009 » C, Pascal
 * Critter 0.42 available by Richard Vida, CCC, October 08, 2009 » Pascal
 * Critter 0.42 : 2649 by Patrick Buchmann, CCC, October 11, 2009

2010 ...
2011 2012 ...
 * Critter 0.52 available by Richard Vida, CCC, Jan 25, 2010 » C
 * Critter 0.52b added to the IPON list ... by Ingo Bauer, CCC, February 04, 2010
 * Strange knight underpromotion by Critter by Richard Vida, CCC, March 04, 2010
 * Critter goes SMP (version 0.60 is released) by Richard Vida,CCC, April 13, 2010
 * Critter 0.60: 2718 by Patrick Buchmann, CCC, April 14, 2010
 * Critter 0.70 is out by Richard Vida, CCC, May 23, 2010
 * Critter 0.80 by Richard Vida, CCC, July 24, 2010
 * Critter 0.90 released by Richard Vida, CCC, November 29, 2010
 * Critter - looking at static evaluation by Richard Vida, CCC, December 11, 2010
 * Critter 1.0 available by Richard Vida, CCC, March 16, 2011
 * Critter 1.0 for Linux by Richard Vida, CCC, March 22, 2011 » Linux
 * My experience with Linux/GCC by Richard Vida, CCC, March 23, 2011
 * Critter bugfix update by Richard Vida, CCC, March 28, 2011
 * Critter 1.2 update + new homepage by Richard Vida, CCC, June 25, 2011 » Android
 * Critter 1.2 SEEMS to be a member of the Ippo family by Kai Laskos, CCC, July 02, 2011
 * for Pascal fans: Critter by Richard Vida, CCC, September 16, 2011
 * Re: World Computer Chess Championship ? by Richard Vida, CCC, June 11, 2012
 * Re: Critter 1.6 released! by Richard Vida, CCC, June 15, 2012
 * Continuation of Critter would be very appreciated by Mike Scheidl, CCC, May 15, 2013

2020 ...

 * OpenCritter compiled for Linux with Free Pascal by Roland Chastain, CCC, November 17, 2020

=External Links=

Chess Engine

 * Critter (chess) from Wikipedia
 * Critter for win32/64, linux and android platforms hosted by Emil Vlasák
 * SourceForge.net: Critter Chess - Project Web Hosting - Open Source Software (Pascal Version)
 * GitHub - rchastain/open-critter: UCI chess engine written in Pascal by Richard Vida hosted by Roland Chastain
 * Critter at CCRL 40/40

Misc

 * Critter (disambiguation page) from Wikipedia
 * Critters (block cellular automaton) from Wikipedia
 * Little Critter from Wikipedia
 * "The Critter" (Chinese pangolin) from Wikipedia
 * Fearsome critters from Wikipedia
 * Critters (film series) from Wikipedia
 * Critters (comics) from Wikipedia

=References= Up one level