Rybka is a computer chess engine designed by International Master Vasik Rajlich. Around 2011, Rybka was one of the top-rated engines on chess engine rating listsIPON ; Ponder ON Rating list and won many computer chess tournaments.
After Rybka won four consecutive World Computer Chess Championships from 2007 to 2010, it was stripped of these titles after the International Computer Games Association concluded in June 2011 that Rybka was plagiarized from both the Crafty and the Fruit chess engines and so failed to meet their originality requirements. In 2015, FIDE Ethics Commission, following a complaint put forward by Vasik Rajlich and chess engine developer and games publisher Chris Whittington regarding ethical breaches during internal disciplinary proceedings, ruled the ICGA guilty and sanctioned ICGA with a warning.
ChessBase published a two-part interview-article about the process and verdict with ICGA spokesperson David Levy. Subsequently, ChessBase recruited Rajlich to produce Fritz 15 (released in late 2015) and Fritz 16 (released in late 2017).
Name The word rybka, pronounced in Czech, means little fish in Czech, Polish, and in many other Slavic languages. Vasik Rajlich was once asked in an interview by Alexander Schmidt, "Did you choose the name Rybka because your program always slipped out of your hands like a little fish?" He replied, "As for the name Rybka – I am sorry but this will remain my private secret."
Internals Rybka is a closed-source program, but still some details have been revealed: Rybka uses a bitboard representation,rybka source code . Rybkaforum.net. Retrieved on October 12, 2013. and is an alpha-beta searcher with a relatively large aspiration window.Rybka Chess Community Forum July 2007 . rybkaforum.net It uses very aggressive pruning, leading to imbalanced search trees.Rybka Chess Community Forum July 2007 . rybkaforum.net The details of the evaluation function are unknown, but since version 2.3.1 it has included work by GM Larry Kaufman on material imbalances, much of which was worked out in a series of papers in the 1990s.Rybka @ Amsterdam 15th WCCC . Rybkaforum.net. Retrieved on October 12, 2013.
Team
Several members of the Rybka team are strong chess players: Vasik Rajlich, the main author of Rybka is an International Master (IM). GM Larry Kaufman is the 2008 Senior Chess World Champion, and from version 2.3 through version 3 was in primary charge of the evaluation function. Iweta Rajlich, Vasik Rajlich's wife and the main Rybka tester is a Women's GM (WGM) and IM. Jeroen Noomen (who used to work on Rebel) and Dagh Nielsen were the authors of its opening book – the latter is one of the world's top freestyle chess players. Both are now less active, and Jiri Dufek is in charge of the book.
History
Vasik Rajlich started working on his chess program at the beginning of 2003. The first Rybka beta was released on December 5, 2005.
Tournament participations In January 2004, Rybka participated in the 6th Programmers Computer Chess Tournament (CCT6) event, placing 53rd out of 54 competers, losing 5 games, drawing 3, and beating the last-place finisher who had 0 points (Tohno).
In April 2004, Rybka participated in Chess War V conducted by Olivier Deville, finishing 23rd in the D Division.
In April 2004, Rybka participated in the Swiss System Season 3 by Claude Dubois, scoring 6 wins, 6 losses and 6 draws in the Top 200 to finish 71st.
Rybka participated in Chess War VI finishing 42nd in the D Division.ChessWar VI D 40m/20' – Final standings after round 11. Open-aurec.com. Retrieved on October 12, 2013. Rybka participated in Chess War VII finishing 48th in the C Division.ChessWar VII C 40m/20' – Final standings after round 11. Open-aurec.com. Retrieved on October 12, 2013. Rybka participated in AEGT round 3, scoring 89 wins, 28 losses and 15 draws.AEGT and Infinite Loop Series. Iggor.110mb.com. Retrieved on October 12, 2013.
In December 2005, Rybka participated in the 15th International Paderborn Computer Chess Championship. Rybka won the tournament with a score of 5½ points out of 7, ahead of other engines such as Gandalf, Zappa, Spike, Shredder and Fruit.
On CCT8 in February 2006, Rybka won with a score of 8 out of 9, going undefeated. In the April 2006 PAL/CSS Freestyle main tournament, an unaided Rybka 1.1 took first place. In the final tournament, Rybka 1.1 finished in second and third place, behind Hydra. In the 6th Leiden ICT in May 2006, Rybka won with a score of 8½ out of 9, ahead of Sjeng, Gandalf and Shredder. At the 14th World Computer Chess Championship in Turin, Italy in May 2006, Rybka, playing under the name Rajlich, finished second, tied with Shredder, after Junior, the winning 2006 World champion. In the June 2006 PAL/CSS Freestyle main tournament, the Rybka team, playing under the handle Rajlich, tied for first place with Intagrand. In the final, the Rybka team took clear first place, a point ahead of the field. All 8 qualifiers for to the final were Rybka users. In the 2006 Dutch open computer chess championship, Rybka 2.2 finished in first place with a perfect score of 9 out of 9. In December 2006, Rybka participated in the 16th International Paderborn Computer Chess Championship. Rybka won the tournament with a score of 6½ points out of 7.
In February 2007, Rybka participated in the CCT9 and won with 6/7. In the 7th Leiden ICT in May 2007, Rybka won with a score of 7½ out of 9, ahead of Zappa and HIARCS. Rybka won the 15th World Computer Chess Championship in June 2007 with a score of 10 out of 11. The Rybka team, playing under the handle Rajlich, won the June 2007 PAL/CSS Freestyle final with a score of 6/9. Later that year it won again the Dutch open computer chess championship, scoring 8/9.
In January 2008, Rybka tied for first place in CCT10 with 5.5/7. In October 2008, Rybka won the 16th World Computer Chess Championship, held in Beijing, China, scoring 8/9. A month later Rybka won the 27th Open Dutch Computer Chess Championship, held in Leiden, scoring a perfect 9/9.
In March 2009, Rybka won CCT11 with 7.5/9CCT11 Final Scoreboard. cctchess.com and the 17th World Computer Chess Championship, held in Pamplona, Spain, with a score of 8/9.
In May 2010, Rybka won the International Computer Chess Tournament in Leiden with 8/9.
Result Summary +Main events Event Year Time controls Result Season 120102ndSeason 220112ndSeason 420133rdSeason 520138th (stage 3)Season 620147th (stage 3)
Odds matches versus grandmasters In March 2007, Rybka played an eight-game match against GM Roman Dzindzichashvili with pawn and move odds. The result was 4–4, after two Rybka wins, four draws and two losses.Rybka vs Dzindzichashvili – information center . Rybkaforum.net. Retrieved on October 12, 2013.
Whilst Rybka has won an 8 game match in March 2007 with GM Jaan Ehlvest which involved giving pawn odds to the human, GM Larry Kaufman of the Rybka team has pledged his own money to a human GM who can beat Rybka in a six-game match without material odds . GM Jaan Ehlvest was again chosen to play Rybka, getting twice the thinking time and white every match, with Rybka having only a three-move opening book, limited (512MB) hash size, and no endgame tablebases (the match being dubbed "Everything but a pawn"). The match, again played in 2007, ended 4.5–1.5 after three Rybka wins and three draws.Rybka vs Ehlvest II – information center. Rybkaforum.net. Retrieved on October 12, 2013.
In September 2008, Rybka played an odds match against Vadim Milov, its strongest opponent yet in an odds match. Milov at the time had an Elo rating of 2705, ranking him 28th in the world. The result was a narrow victory to Milov: In two standard games (Milov played White, no odds), Milov lost the first game and drew the second one. Then they played two games at the classical "pawn and move" handicap (f7 removed). The first game ended in an early draw by perpetual check, while the second was won by Milov. Finally they played four games at odds of the exchange (Rybka removed a1 rook, Milov b8 knight); here Rybka drew three times and lost once. The final score was 4.5–3.5 for Milov.The Milov vs. Rybka Handicap Match, Chessbase, September 24, 2008
Zappa match In September 2007, Zappa defeated Rybka in a match, –. Two famous games were played in this match. The first was the 180-move fourth game, which was approaching a draw under the 50-move rule. However, due to an incorrect evaluation by the Rybka engine, at move 109 it moved a pawn to avoid a draw (even though Zappa could, and did, immediately take the pawn), thus resetting the counter for that rule. The loss of the pawn eventually allowed Zappa to whittle away Rybka's defenses and win the game.PGNs of game 3 and 4 with Rybka evaluation, Zappa won both . Rybkaforum.net. Retrieved on October 12, 2013. Then in game 9, Rybka was 3 pawns up with a totally won position, but played a horrific blunder on move 71, "the worst blunder in modern computer chess",Cozzie, Anthony Zappa fillets the Fish as it lacked sufficient knowledge to see a draw would ensue by opposite-color bishops. Zappa had this knowledge, took advantage, and drew the game. Anthony Cozzie thanked his operator Erdogan Gunes for having the wherewithal to stay until the end in these two games, rather than agree to a draw in game 4 or resign in game 9.
The match came about after Vasik Rajlich made a $100,000 publicity challenge to the FIDE champion Fritz or Junior, even offering odds of a game in a 24-game match (13 points).An Open Letter and $100,000 challenge. Rybkachess.com. Retrieved on October 12, 2013. But negotiations between Rybka and Junior broke down due to disputes over on-site machines.Levy, David A Lost Opportunity. chessninja.com The match was changed to 10 games against Zappa, with $10,000 the amount eventually paid to the winner.
Versions
Version 3 Rybka 3 was released on August 6, 2008. While previous versions of Rybka were released exclusively by Convekta, Rybka 3 was released by both Chessbase and Convekta."A 'Little Fish' (Rybka) in Corporate Waters". chessvine.com. July 19, 2008 Although still a UCI engine, Rybka 3 has extra features when run under the ChessBase and Convekta user interfaces. In an interview with Frank Quisinsky, Vasik Rajlich revealed plans for a future GUI that would "properly display chess knowledge to the user" most likely in the form of graphical evaluation of the pieces on the board. The GUI, named Aquarium, has been released by ChessOK (formerly known as Convekta).Rybka Aquarium: Interview with the Developers. chessok.com. July 23, 2008
Version 4 Rybka 4 was released May 26, 2010. Vasik Rajlich has given the following information at the Rybka forum:Rybka 4 update . Rybkaforum.net. Retrieved on October 12, 2013. Rybka 4 is a normal UCI engine, without copy protection. There are separate single-processor and multi-processor versions. Full chess analysis packages which include Rybka 4 will be made by ChessBase (www.chessbase.com) and Convekta/ChessOK (www.chessok.com). Plain Rybka 4 UCI without GUI for download only is available from RybkaChess (www.rybkachess.com). All of these versions of Rybka 4 will be identical and can be used in any UCI-compliant GUI.
Remote Rybka Vasik Rajlich has now released "Remote Rybka" which is a special version of Rybka (4+ or cluster) on very powerful hardware / clusters run by Lukas Cimiotti.Rybka Cluster – for the elite chess player. Rybkachess.com (February 1, 2011). Retrieved on October 12, 2013. This can be rented for a specific period of time, though currently not less than 2 days due to overhead costs. Upon renting one has access to the Remote Rybka from one's PC, and all details of rentals are strictly private.
Version 4.1 This was a version swiftly produced after the ICGA investigation was announced, to ensure no infidelities in code sourcing. It was released on March 5, 2011.
Future