Rybka

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Rybka 4 Logo [1]

Rybka,
a chess engine by primary author Vasik Rajlich, from 2007 until 2010 dominating and reigning World Computer Chess Champion and holder of the Shannon Trophy, winning the WCCC 2007 [2] , WCCC 2008, WCCC 2009 and WCCC 2010, but in June 2011 disqualified by the ICGA from all previous and future World Computer Chess Championships. 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.

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 [3] .

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 [4] [5] and the first commercial version, Rybka 1 [6] end of 2005 was a sensation, and Rybka soon became the dominating program leading rating lists by a huge margin [7] [8] . 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 [9] , from ChessOK optional with the Aquarium GUI [10] , or from ChessBase packaged with the Fritz GUI [11] . The demo version Rybka 2.3.2a can be downloaded for free [12] .

Achievements

Year Tournament Rank/From Title/Remarks
2004 CCT6 50/54
2005 IPCCC 2005 b 1/12
2006 CCT8 1/38
ICT 2006 1
WCCC 2006 3/18 as Rajlich, disqualified 2011
DOCCC 2006 1
IPCCC 2006 1/10
2007 ACCA 2007 1/16
CCT9 1/54
ICT 2007 1
WCCC 2007 1/12 World Computer Chess Champion, disqualified 2011
DOCCC 2007 1/14
IPCCC 2007 2/10
2008 ACCA 2008 1/18
ICT 2008 1
WCCC 2008 1/10 World Computer Chess Champion, disqualified 2011
DOCCC 2008 1/10
2009 ACCA 2009 1/12
WCCC 2009 1/10 World Computer Chess Champion, disqualified 2011
DOCCC 2009 1/9
2010 ICT 2010 1/14
WCCC 2010 1/10 World Computer Chess Champion, disqualified 2011
DOCCC 2010 1/20
2012 ICT 2012 1/8

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 [13] .

for (bb_t knights = Board.pieces [WN]; knights; knights &= knights-1)
{
    int knight_sq = bit_scan (knights);
    for (bb_t captures = knight_moves [knight_sq] & opponent_pieces; captures; captures &= captures - 1)
    {
        int capture_sq = bit_scan (captures);
        *moves ++ = move (knight_sq, capture_sq);
        *values++ = Board.sq [capture_sq] * 256 + 192;
    }
}

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 [14] [15] , other implementation details were released to the public, such as material- and material imbalance tables, aggressive LMR, razoring [16] and some variation of singular extensions [17] . Zach Wegner elaborated on evaluation issues, and compared Rybka 1 beta with Fruit's evaluation [18] , continued by former anonymous author "BB+" alias Mark Watkins in February 2011 [19] .

Release Dates

  • Rybka 1.0 beta : 2005-12
  • Rybka 1.0 :
  • Rybka 1.1 : 2006-04
  • Rybka 1.2 : 2006-06
  • Rybka 1.5 :
  • Rybka 1.6.1 :
  • Rybka 2.0 :
  • Rybka 2.2 : 2006
  • Rybka 2.2n2 : 2006-12
  • Rybka 2.3 : 2007-01
  • Rybka 2.3.1 : 2007-02
  • Rybka 2.3.2a : 2007-06
  • Rybka 3 : 2008-08
  • Rybka 4 : 2010-05
  • Rybka 4.1 : 2011-3

Controversies

Rybka 1.0 and Fruit

Rajlich's interpretation of nodes and depth [20] [21] [22] [23] [24] , and the controversy about Strelka [25] [26] raised suspicions about the initial origin of Rybka 1.0 [27] [28] , but Vasik Rajlich categorically denied Rybka 1.0 was based on Fruit [29] [30] , as mentioned by Chrilly Donninger in 2005 [31] after early rumors [32] and questions [33] arose.

Vasik Rajlich's most quoted statement in these discussions was probably from an interview in uciengines.de, December 20, 2005 [34] :

Yes, the publication of Fruit 2.1 was huge. Look at how many engines took a massive jump in its wake: Rybka, Hiarcs, Fritz, Zappa, Spike, List, and so on. I went through the Fruit 2.1 source code forwards and backwards and took many things.
...
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 [35] without any substantiation and evidence, caused further discussions [36] .

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 [37] [38] [39] .

On February 19, 2011 ICGA president David Levy broached on cloning issues in a ChessVibes column [40] . 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 [43] and elsewhere [44] [45] . The German sites Heise online [46] and Spiegel Online broached the issue [47] .

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 [48] [49] and Le Fou numérique [50] , contain a substantial amount of Crafty code [51] , confirmed by Robert Hyatt [52] [53] . Beside other evidence there are the known bugs in the old Crafty code (if ms == 99999) [54] that caused El Chinito by primary author Eugenio Castillo Jiménez to be exposed as a clone [55] [56] .

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 [57] .

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 [58] , see ICGA Investigations

See also

Publications

Forum Posts

2004

2005

2006

2007

2008

2009

2010

2011

Attack of the clones | ChessVibes by David Levy, February 19, 2011

2012

External Links

Rybka

Controversy

A Gross Miscarriage of Justice in Computer Chess (part two) by Søren Riis, ChessBase News, January 03, 2012 [72]
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 [73]
ICGA/Rybka controversy: An interview with David Levy (2), ChessBase News, February 10, 2012

Misc

References

  1. Rybka - for the serious chess player - Purchase Rybka
  2. Bulletin Day 7 WCCC 2007 (ICGA Tournaments)
  3. Rybka - for the serious chess player - Rybka team
  4. Rybka 1.0 beta release - need testers by Vasik Rajlich, CCC, November 30, 2005
  5. Rybka Beta 1.0 - Chess.com
  6. Rybka 1.0 Announcement by Vasik Rajlich, CCC, December 05, 2005
  7. SSDF Rating List 2007-04-21 by Thoralf Karlsson, CCC, April 21, 2007
  8. CEGT Quad Versions 40/120 (AMD 3500+/4200+)
  9. Rybka - for the serious chess player - Purchase Rybka
  10. Rybka & Aquarium - ChessOK shop
  11. Chess software - Rybka 4 from ChessBase
  12. Rybka - for the serious chess player - Download Rybka 2.3.2a
  13. re: rybka source code by Vasik Rajlich, Rybka Forum, July 24, 2007
  14. Strelka 2.0 by Vasik Rajlich, Rybka Forum, January 11, 2008
  15. My recent correspondence with Vasik Rajlich by Sven Schüle, CCC, June 13, 2010
  16. Re: Strelka 2.0 pg 4 by Anthony Cozzie, Rybka Forum, January 11, 2008
  17. A question to Larry Kaufman, by Erik, Rybka Forum, December 30/31, 2009
  18. Re: What do you folks make of this ? by Chris Whittington, OpenChess Forum, June 27, 2010
  19. Mark Watkins (2011). A comparison of Rybka 1.0 Beta and Fruit 2.1, pdf, February 24, 2011 Version
  20. What Strelka tells about Rybka's nodecount and depth by Ernest Bonnem, CCC, July 09, 2007
  21. Does Rybka Properly Count Positions Evaluated? by John L. Jerz
  22. To Jeroen and interested minds, re. Tiger node count by Christophe Théron, CCC, August 15, 2008
  23. Re: Question to Larry Kaufman about Rybka by Larry Kaufman, CCC, February 05, 2010
  24. Node counting by BB+, OpenChess Forum, January 20, 2011
  25. Strelka = Rybka 1.0 by DarkAvenger, Rybka Forum, July 07, 2007
  26. Strelka 2.0 by Vasik Rajlich, Rybka Forum, January 11, 2008
  27. Rybka 1.0 vs. Strelka by Zach Wegner, CCC, August 19, 2008
  28. Questions for Vas by Zach Wegner, CCC, August 25, 2008
  29. Re: Is Rybka a derivative of Fruit? by Vasik Rajlich, Rybka Forum, July 14, 2007
  30. question to vas on similarity of rybka 1.0 to fruit by duncan, Rybka Forum, August 25, 2008
  31. Rybka uses PVS and not MTD(f). Its no Fruit-Clone by Chrilly Donninger, CCC, December 12, 2005
  32. Is Rybbka a fruit clone? by Ziad Haddad, CCC, December 06, 2005
  33. Rybka - How much Fruit is inside? by Daniel Mehrmann, CCC, December 11, 2005
  34. Interview with Vasik Rajlich by Christopher Conkie, Michael Diosi, Frank Quisinsky & Alexander Schmidt, December 20, 2005, hosted by Ed Schröder
  35. Official statement on [Deleted?] by Vasik Rajlich, Rybka Forum, October 21, 2009
  36. I'm in doubt if RobboLito is a clone by Volker Pittlik, CCC, October 24, 2009
  37. Fabien's open letter to the community by Tord Romstad, CCC, January 23, 2011
  38. Fabien's open letter to the community by Tord Romstad, OpenChess Forum, January 23, 2011
  39. The Chess Mind Blog - More Computer Chess Controversy
  40. Attack of the clones | ChessVibes by David Levy, February 19, 2011
  41. In retrospect by Rebel, Rybka Forum, July 14, 2011
  42. Apology to Vas by Rebel, Rybka Forum, August 17, 2011
  43. ICGA Investigations Wiki
  44. Open letter to the ICGA about the Rybka-Fruit issue by Harvey Williamson, Hiarcs Forum, March 01, 2011
  45. Programmers Open Letter to ICGA on Rybka/Fruit by BB+, OpenChess Forum, March 01, 2011
  46. Plagiatsvorwurf gegen Computerschach-Weltmeister, Heise online, March 01, 2011 (German)
  47. Schach-Software Rybka - Programmierer vermuten Intelligenzklau by Frank Patalong, Spiegel Online, March 03, 2011 (German)
  48. RYBKA 1.6.1 in Chess War V-VII
  49. Re: Programmers Open Letter to ICGA on Rybka/Fruit by Olivier Deville, Openchess Forum, March 05, 2011
  50. Le Fou numérique - Le Système du Suisse 3 - T
  51. Re: Programmers Open Letter to ICGA on Rybka/Fruit by BB+, OpenChess Forum, March 05, 2011
  52. Re: Programmers Open Letter to ICGA on Rybka/Fruit by Robert Hyatt, Openchess Forum, March 05, 2011
  53. Rybka 1.6.1 by Robert Hyatt, Rybka Forum, March 13, 2011
  54. Re: Programmers Open Letter to ICGA on Rybka/Fruit byBB+, OpenChess Forum, March 04, 2011
  55. Re: Correction: List and ElChinito as Crafty clones, ... etc by Paul H, CCC, August 21, 2004
  56. Open letter by Eugenio Castillo (ELChinito team) ... by Frank Quisinsky, CCC, August 28, 2004
  57. Rybka disqualified and banned from World Computer Chess Championships | ChessVibes by Peter Doggers, June 29, 2011
  58. Rybka and the ICGA, CSVN Computerschaak
  59. BB's Rybka/Ippolit comparison by Zach Wegner, OpenChess Forum, June 13, 2010
  60. Feb 12 version: Rybka 1.0 Beta / Fruit 2.1 document by BB+, OpenChess Forum, February 12, 2011
  61. Rybka evidence recapitulation by BB+, OpenChess Forum, January 03, 2012
  62. Part 1 covers Houdini, Rybka, Komodo, Stockfish, Critter, Naum, Chiron and Spike
  63. A Pairwise Comparison of Chess Engine Move Selections by Adam Hair, hosted by Ed Schröder
  64. Anthony Cozzie speaks about Rybka source code from Steve Lim / SuperSteve3d - Home, February 04, 2008
  65. Why did the ICGA ignore this advice? by John Sidles, Rybka Forum, July 06, 2011
  66. Re: A Big Thanks and a Small Update by John Sidles, Rybka Forum, January, 08, 2012
  67. Voir dire from Wikipedia
  68. Fruit 2.1 and Rybka 1.0 Beta 1.0 decompiled source code by Ed Schröder
  69. ChessBase: A Gross Miscarriage of Justice in Computer Chess by kingliveson, OpenChess Forum, January 02, 2012
  70. Re: ChessBase: A Gross Miscarriage of Justice in Computer Chess by BB+, OpenChess Forum, January 02, 2012
  71. Re: Hyatt Is Gone! by BB+ OpenChess Forum, Jan 03, 2012
  72. Rybka evidence recapitulation by BB+, OpenChess Forum, January 03, 2012
  73. Søren Riis (2012). A Gross Miscarriage of Justice in Computer Chess. pdf hosted by ChessBase

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