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Portions not contributed by visitors are Copyright 2018 Tangient LLC
TES: The largest network of teachers in the world
a chess engine by primary author Vasik Rajlich, since 2007 dominating and reigning World Computer Chess Champion and holder of the Shannon Trophy, winning the WCCC 2007 [1] , WCCC 2008, WCCC 2009 and WCCC 2010, but in June 2011 disqualified by the ICGA from all previous and future World Computer Chess Championships [2] . Rybka further won various IPCCC, Dutch Open Computer Chess Championships, International CSVN Tournaments and on-line tournaments such as CCT Tournaments and ACCA Americas' Computer Chess Championships. Rybka is a standalone chess engine supporting the UCI protocol.
Table of Contents
Screenshots
Team
The Rybka team consists of primary author and International Master Vasik Rajlich, supported by Grandmaster and evaluation expert Larry Kaufman (Rybka 3), Rybka's main tester and Women's GM (WGM) and IM Iweta Rajlich, the opening book authors Jeroen Noomen, Dagh Nielsen, Jiří Dufek and Nick Carlin, as well as Rybka primary tournament operator Hans van der Zijden, hardware expert Lukas Cimiotti and Webmaster and Webdesigner Felix and Christoph Kling [6] .Versions
Vasik Rajlich started developing Rybka in about 2003, and worked full-time on it since 2005. The appearance of the free Rybka 1 beta [7] [8] [9] and the first commercial version, Rybka 1 [10] end of 2005 was a sensation, and Rybka soon became the dominating program leading rating lists by a huge margin [11] [12] . Rybka 3 was developed in collaboration with Larry Kaufman, the most recent and strongest version Rybka 4 and the parallel version Deep Rybka 4 appeared in April 2010, market as standalone chess engine from RybkaChess.com [13] , from ChessOK optional with the Aquarium GUI [14] , or from ChessBase packaged with the Fritz GUI [15] . The demo version Rybka 2.3.2a can be downloaded for free [16] .Achievements
[17]Program Internals
Rybka is a bitboard engine, first versions rotated, Rybka 4 apparently magic bitboards for sliding piece attack and move generation. Vasik once posted a snippet of Rybka source-code, a typical bitboard serialization loop to generate white knight captures [18] .Due to the disputed open source engines Strelka 2.0 and later Ippolit, which accordant to Vasik Rajlich were both based on or heavily influenced by re-engineered Rybka executables [19] [20] , other implementation details were released to the public, such as material- and material imbalance tables, aggressive LMR, razoring [21] and some variation of singular extensions [22] . Zach Wegner elaborated on evaluation issues, and compared Rybka 1 beta with Fruit's evaluation [23] [24] , continued by former anonymous author "BB+" alias Mark Watkins in February 2011 [25] .
Release Dates
Controversies
Rybka 1.0 and Fruit
Rajlich's interpretation of nodes and depth [26] [27] [28] [29] [30] , and the controversy about Strelka [31] [32] raised suspicions about the initial origin of Rybka 1.0 [33] [34] , but Vasik Rajlich categorically denied Rybka 1.0 was based on Fruit [35] [36] , as mentioned by Chrilly Donninger in 2005 [37] after early rumors [38] and questions [39] arose.Vasik Rajlich's most quoted statement in these discussions was probably from an interview in uciengines.de, December 20, 2005 [40] :
...
Anyway, if I really had to give a number - my wild guess is that Rybka would be 20 rating points weaker had Fruit not appeared.
Ippolit
The appearance of the Ippolit open source program by pseudonymous authors in May 2009, and Rajlich's claim it is a clone of Rybka 3 [41] without any substantiation and evidence, caused further discussions [42] .Open Letters
In January 2011, Fabien Letouzey confirmed that Strelka, the allegedly clone of Rybka, was not a verbatim copy of the source code from Fruit, but a bitboard re-write of Fruit with some other ideas, and not just an extraction of a couple of ideas [43] [44] [45] .On February 19, 2011 ICGA president David Levy broached on cloning issues in a ChessVibes column [46] . In March 2011, following computer chess programmers signed an open letter to David Levy, Jaap van den Herik and the board of the ICGA, to support the claim Rybka 1.0 beta and subsequent versions were allegedly derivatives from Fabien Letouzey’s program Fruit 2.1:
The letter was published in the private ICGA Investigations Wiki [49] and elsewhere [50] [51] [52] . The German sites Heise online [53] and Spiegel Online broached the issue [54] .
Pre-Beta Rybka and Crafty
In February and March 2011, evidence was found by Zach Wegner and Mark Watkins that pre-Beta Rybka, which played the CCT6 in January 2004, and competed in tournaments of Engine Rating Lists such as ChessWar [55] [56] and Le Fou numérique [57] , contain a substantial amount of Crafty code [58] , confirmed by Robert Hyatt [59] [60] . Beside other evidence there are the known bugs in the old Crafty code (if ms == 99999) [61] that caused El Chinito by primary author Eugenio Castillo Jiménez to be exposed as a clone [62] [63] .Disqualification
In June 2011, the ICGA has disqualified and banned Rybka and its programmer Vasik Rajlich from previous and future World Computer Chess Championships. The ICGA accuses Rajlich of plagiarizing two other programs, Crafty and Fruit, and demands that he returns the trophies and prize money of the World Computer Chess Championships in 2007, 2008, 2009 and 2010 [64] .In August 2011, the board of the Dutch Computer Chess Federation (CSVN) declared the most serious doubts as to the rightfulness of ICGA's decision. Therefore, they have chosen not to abide by their sanctions against Rybka [65] , see ICGA Investigations
See also
Publications
Forum Posts
2004
2005
2006
2007
2008
2009
2010
2011
2012
External Links
Rybka
Controversy
A Gross Miscarriage of Justice in Computer Chess (part two) by Søren Riis, ChessBase News, January 03, 2012 [80]
A Gross Miscarriage of Justice in Computer Chess (part three) by Søren Riis, ChessBase News, January 04, 2012
A Gross Miscarriage of Justice in Computer Chess (part four) by Søren Riis, ChessBase News, January 05, 2012 [81]
ICGA/Rybka controversy: An interview with David Levy (2), ChessBase News, February 10, 2012
References
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