Rybka

The word Rybka means the same in Czech and Polish as in Russian: "fish". In an interview to Alexander Schmidt’s question: “You chose the name Rybka because the program always slips out of your hands like a fish?” Vasik Reilich answered: “As for the name Rybka, I apologize, but this will remain my little secret.” ^[10]

Version 2.2n2 ( available for free download ) had a rating of 3110 Elo ^[11] on a 4-core processor, and Rybka 3 was about 100 points stronger than 2.2n2 ^[12] . The current version of Rybka uses multiprocessing, increasing the rating by about 50 Elo points while doubling the number of processors ^[13] .

The evaluation function of Rybka is considered by developers as one of the main advantages among competing programs ^{[14] [15]} .

Using the bitwise representation of board cells increases efficiency by 60% when run in 64-bit mode, which in turn leads to approximately 40 additional Elo rating points ^[16] .

On September 26, 2008, the SSDF rating list was released, with Deep Rybka 3 in first place with a rating of 3238 ^[17] .

Rybka is a closed- source program , but some details are known: Rybka uses a bitwise representation of chess positions ^[18] and alpha-beta clipping with a relatively large “ aspiration search window ” ^[19] . It uses a very aggressive reduction of possible solutions, which leads to unbalanced search trees ^[20] . Details of the evaluation function are unknown, but starting from version 2.3.1, it uses the ideas of Grandmaster Larry Kaufman , most of which was proposed in his publications of the 1990s on material imbalance ^{[16] [21]} .

In 2007, Rybka was accused of being based on the Fruit program, but Reilich categorically rejected this claim ^[22] .

Rybka’s team is unusual among the creators of computer chess programs - there are many strong chess players among its main participants ^[16] . Vasik Reilich , the main author of Rybka, is an international master (IM). ^[23] International Grandmaster (GM) Larry Kaufman ^[24] , who won the 2008 World Championship for Veterans (over 60 years old), starting with version 2.3, is responsible for the evaluation function. Iveta Reilich , the main test and ideological inspirer of the Rybka program, is a female grandmaster (WGM) and international master (IM) ^[25] . Jeroen Nomen ^[26] (who used the REBEL program in his work) and Doug Nielsen ^[27] , the authors of the debut books are the strongest players in advanced chess .

Vasik Reilich began work on the creation of a computer chess program in early 2003 . On December 2, 2005, a beta version of Rybka 1.0 was released.

Tournaments

In 2005, from December 27 to December 30, Rybka participated in the 15th Paderborn International Computer Chess Championship (IPCCC). Rybka won the tournament with 5½ points out of 7 possible, ahead of programs like Gandalf , Zappa , Spike , Shredder and Fruit .

At the Internet Chess Championship (CCT8), which was held from February 25 to February 26, 2006 , Rybka won by scoring 8 points out of 9 possible, playing without defeat. In April 2006, Rybka 1.1 took first place in the main PAL / CSS Freestyle tournament, playing without human help. In the final tournament, Rybka 1.1 shared second and third place, after Hydra . In the 6th ICT Tournament in Leiden in May 2006, Rybka won by scoring 8½ out of 9 and beating Sjeng , Gandalf and Shredder . At the 14th World Chess Championship in Turin (Italy) in May 2006, Rybka, playing under the name Rajlich , shared second place with the Shredder program, which she drew after the Junior program, which won the 2006 World Champion title. In June 2006, in the main PAL / CSS Freestyle tournament, the Rybka team, playing under the name Rajlich, shared first place with Intagrand . In the final, Rybka took a clean first place. In 2006, Rybka 2.2 became the first at the Netherlands Open Chess Open Computer Chess Championship (ODCCC) with a maximum score of 9 out of 9 possible ^[28] . In December 2006, Rybka participated in the 17th IPCCC. Rybka won the tournament with 6½ points out of 7 possible ^[29] .

In February 2007, Rybka participated in the CCT9 tournament and won it with 6/7 points ^[30] . In the 7th ICT Tournament in Leiden in May 2007, Rybka won with 7½ of 9 points ahead of Zappa and HIARCS ^[31] . Rybka won the 15th World Chess Championship among computer programs in June 2007 with 10 points out of 11 possible. The Rybka team, playing under the name Rajlich, won the PAL / CSS Freestyle tournament in June 2007, finishing with 6/9 points. Later that year, she again won the ODCCC, gaining 8/9 points ^[32] .

In January 2008, Rybka took first place in the CCT10, gaining 5.5 / 7 points ^[33] . In October 2008, Rybka won the 16th Computer Chess World Championship , held in Beijing , China , by typing 8/9. A month later, Rybka won the 28th ODCCC, gaining a maximum of 9/9 points. ^[34]

In March 2009, Rybka won CCT11 with 7.5 / 9 points ^[35] and the 17th World Chess Championship among computer programs ( Pamplona , Spain ), gaining 8/9 points ^[36] . In October 2009, Rybka won the 29th ODCCC with a score of 7.5 / 9 ^[37] .

Handicap matches Fish vs Grandmasters

After Rybka was the first among the programs to win a handicap match with a grandmaster (against Jaan Elvest , who was offered a handicap by pawn), Larry Kaufman from Rybka promised his own cash prize if a person could win Rybka in a match of six games without a handicap . Grandmaster Jaan Elvest later re-played with Rybka, having a double advantage in time for thinking over moves and white in each game, while Rybka had a three-way debut book, a limited cache size (512 MB) and did not have access to the endgame database (the match was called “Everything but a pawn”). The match ended with a score of 4.5-1.5 after three victories for Rybka and three draws ^[38] .

In March 2008, Rybka played a handicap match of eight games against grandmaster Roman Dzhindzhikhashvili with black “without a pawn and no move,” from March 3 to March 8. The result was 4–4, after 2 victories of Rybka, 4 draws and 2 defeats ^[39] .

In September 2008, Rybka played a handicap match against grandmaster Vadim Milov , his strongest opponent in such matches (Milov at that time had an Elo rating of 2705, 28th in the world). The result was a man’s victory, which Milov had difficulty. In two games without a handicap, Milov lost to Rybka with a white 1½-½. Having the advantage of "pawn and move" he won 1½-½. He also defeated 2½-1½ (3 draws, 1 victory), playing black without a knight, and Rybka without a rook ^[40] .

Match with Zappa

In September 2007, the Zappa chess program defeated Rybka in the match with a score of 5½-4½. The key was the 180-way fourth game ^[41] , which could end in a draw subject to the rule of 50 moves . However, in order to avoid a draw on move 109 due to this rule, Rybka sacrificed her pawn due to the peculiarity of the program. The loss of the pawn eventually allowed Zappa to nullify Rybka’s defenses and win the game. ^[42]

• 2010-05-26 Rybka 4
• 2008-07-29 Rybka 3 UCI
• 2007-06-19 Rybka 2.3.2a UCI
• 2007-03-02 Rybka 2.3.1 UCI
• 2007-02-15 Rybka 2.3 and 2.3LK (Larry Kauffman) UCI
• 2006-11-10 Rybka 2.2 UCI
• 2006-09-26 Rybka 2.1o UCI
• 2006-07-17 Rybka 2.1 UCI
• 2006-06-10 Rybka 2.0 Beta
• 2005-10 Rybka 1.0 Beta

Version 3

While previous versions of Rybka were exclusively released by Convekta , Rybka 3 was jointly released by ChessBase and Convekta. ^[43] Although Rybka 3 remains a chess program with a UCI interface, it has additional features when executed in a ChessBase or Convekta user shell. ^[44] In an interview with Frank Kuizinsky, Vasik Reilich spoke about plans for the future graphical user interface (GUI), which “will properly display chess knowledge to the user”, most likely in the form of a graphical evaluation of the pieces on the board. A graphical user interface called Aquarium (Aquarium) was released by ChessOK , formerly known as Convekta ^[45] .

Chess960 (Fischer chess) support was provided for the 2007 Mainz chess tournament, where Rybka subsequently won the Fischer computer chess tournament ^{[46] [47]} .

There have been many general enhancements to the power of the game, including improved multiprocessor performance, increased search efficiency, and better position rating. Three programming styles have been created: optimal, human, and dynamic. The debut book is now sold as a separate product ^[44] . Rating lists of chess programs showed that Rybka 3 exceeds the rating of the previous version of Rybka by almost 100 Elo points ^[48] .

Version 4

• Rybka 4 was released on May 26, 2010. Vasik Reilich gave the following information on the Rybka forum: ^[49]
  • Rybka 4 is a normal UCI engine, without copy protection.
  • There are separate uniprocessor and multiprocessor versions.
  • Complete chess analysis packs that Rybka 4 includes will be made by ChessBase (www.chessbase.com) and Convekta / ChessOK (www.chessok.com).
  • Regular Rybka 4 UCI without a graphical user interface (GUI) is only available for download from RybkaChess (www.rybkachess.com).
  • All of these versions of Rybka 4 will be identical and can be used in any UCI-compatible GUI.

Future Add-ons

• Native Linux support has been confirmed without a specific date. A program release plan for non- Windows platforms is expected after Rybka version 3.0 is completed. However, Rybka runs on Wine software , and the 64-bit Rybka runs on both Linux and Mac OS X using an experimental, Rybka-specific level of translation called “microwine” ^[50] .
• Support for Pocket PC and similar mobile devices ^[51] .

Reilich claimed that Rybka will continue to use open protocols, both for normal operation and for the data provided by Rybka 3 GUI.

In May 2007, a new Strelka chess program appeared, proposed by Yuri Osipov . Soon, allegations arose that Strelka was a clone of Rybka 1.0 beta in the sense that it was a redesigned and slightly modified version of Rybka. ^[52] Some of the chess players found that Strelka had an identical analysis with Rybka in many different situations, in some cases even the same mistakes and weaknesses. Osipov, however, has repeatedly stated in forums that Strelka was based on Fruit, not Rybka, and that any similarities were either because Rybka was also based on Fruit, or because of the rating function settings made close to Rybka as far as it's possible. ^{[53] [54]}

With the release of Strelka 2.0 beta, source code was included. V. Reilich, creator of Rybka, stated the “evidence” that Strelka 2.0 beta was a clone of Rybka 1.0 beta, although not without some improvements to certain areas. Based on this, he called the code his own and intended to re-release it under his own name ^[55] , although he did not do it later. He also claimed that “Yuri Osipov” was a pseudonym.

According to Victor Zakharov (Convekta company) in his review for the Arena chess website: “I believe that Yuri Osipov (Ivanovich) is the real name. He did not hide it. However, I cannot say this with a 100% guarantee. ”He also contacted Yuri Osipov a little to develop a mobile platform for chess programs ^[56] .

However, the author of Fruit, Fabian Letuzier, clearly expressed in an open letter mentioned above that Strelka 2.0 beta is a derivative of Fruit with some minor changes ^[57] .

The IPPOLIT chess program was released in October 2009 with its source code. Some testers argue that IPPOLIT is stronger than Rybka 3 ^{[58] [59]} , while other independent sources claim that Rybka and IPPOLIT have roughly the same power when running on a single main CPU. Vasik Reilich , the author of Rybka, cited that IPPOLIT may be a decompiled version of Rybka, and that the people involved kept him informed of their progress via email. ^[60] As of October 2009, there is no definitive evidence regarding the origin of IPPOLIT, whether it is an original work or a clone. Despite Reilich’s opinion, there is a claim that IPPOLIT is not a Rybka clone due to significant differences, such as a smaller used memory area and different endgame knowledge, especially the ability to turn a pawn into an elephant that is not supported by Rybka ^[61] .

In 2011, a panel of 34 chess developers accused Rybka of borrowing the open source code from Crafty and Fruit . As a result, the executive committee of the International Association of Computer Games demanded that Vasik Reilich return all previously received awards and prize-winning chess competitions. It was announced that the program will not be allowed for future world championships; The WCCC recommended that other competition organizers also refuse Rybka ^{[8] [9]} .

• Official release Rybka 4
• Official webpage
• Official forum
• Rybka Settings List
• Rybka game on ChessGames.com
• Game against Rybka
• CCRL Rating List
• CEGT Rating List
• Interview with Rybka 3 developers
• Interview with the author of the debut book Rybka