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Rybka (Computer)
Number of games in database: 213
Years covered: 2005 to 2016
Overall record: +141 -31 =41 (75.8%)*
   * Overall winning percentage = (wins+draws/2) / total games.

Repertoire Explorer
Most played openings
B90 Sicilian, Najdorf (9 games)
C42 Petrov Defense (7 games)
D43 Queen's Gambit Declined Semi-Slav (5 games)
000 Chess variants (5 games)
B28 Sicilian, O'Kelly Variation (5 games)
B51 Sicilian, Canal-Sokolsky (Rossolimo) Attack (4 games)
D47 Queen's Gambit Declined Semi-Slav (4 games)
C92 Ruy Lopez, Closed (4 games)
C78 Ruy Lopez (4 games)
E15 Queen's Indian (3 games)

   🏆 TCEC Season 9 (stage 1a)
   Fizbo vs Rybka (May-20-16) 0-1
   Rybka vs Gull (May-19-16) 1-0
   Rybka vs Texel (May-17-16) 1-0
   Ginkgo vs Rybka (May-17-16) 1/2-1/2
   Hannibal vs Rybka (May-14-16) 0-1

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(born 2004) Czech Republic

[what is this?]
Rybka (Czech for "little fish") is a computer chess engine designed by IM Vasik G Rajlich. It supports both single processor and SMP systems. Iweta Radziewicz Rajlich is the main tester & Hans van der Zijden is one of her operators. Jeroen Noomen & Jiri Dufek co-authored her opening book. At the WCCC 2006 (2006), Rybka, playing under the name Rajlich, tied for 2nd place with Shredder (Computer), and behind the champion, Junior (Computer). Rybka won the 15th World Computer Chess Championship in Amsterdam, 2007 and the 16th World Computer Chess Championship in Beijing, September 28th to October 5th 2008 with 8.0/9 (+7 -0 =2). During 2009-10, she also became the World Computer Speed Chess Champion.

In 2011, the International Computer Games Association (ICGA) ruled that Raljich had plagiarized two other programs, Crafty and Fruit, disqualified him for life from competing in the World Computer Chess Championship and all other ICGA events, and stripped Rybka of the championship titles it had won in 2006 through 2010.

 page 1 of 9; games 1-25 of 213  PGN Download
Game  ResultMoves YearEvent/LocaleOpening
1. Spike vs Rybka 1-069200515. IPCCCE39 Nimzo-Indian, Classical, Pirc Variation
2. Rybka vs Jonny 1-0212005Blitz:110'C69 Ruy Lopez, Exchange, Gligoric Variation
3. Rybka vs Shredder ½-½572005IPCCCB81 Sicilian, Scheveningen, Keres Attack
4. Zappa vs Rybka 0-1772005IPCCCE12 Queen's Indian
5. Rybka vs Argonaut 1-0372005IPCCCC68 Ruy Lopez, Exchange
6. Rybka vs Gandalf 1-0462005?B12 Caro-Kann Defense
7. Ikarus vs Rybka 0-1572005IPCCCB00 Uncommon King's Pawn Opening
8. Shredder vs Rybka 0-1412006WBEC13 Premier Division,C50 Giuoco Piano
9. Ktulu vs Rybka  0-1502006Sonnabend_Div.Hardware_30minD43 Queen's Gambit Declined Semi-Slav
10. Rybka vs Granda Zuniga 1-0472006Torre ENTEL PCSB18 Caro-Kann, Classical
11. Leitao vs Rybka ½-½432006Torre ENTEL PCSD37 Queen's Gambit Declined
12. Rybka vs M Flores 1-0252006Copa Entel ,E10 Queen's Pawn Game
13. J Hellsten vs Rybka 0-1642006Torre ENTEL PCSD36 Queen's Gambit Declined, Exchange, Positional line, 6.Qc2
14. Rybka vs E Arancibia  1-0472006Copa Entel ,B07 Pirc
15. O Zambrana vs Rybka  0-1342006Copa Entel ,B41 Sicilian, Kan
16. R Felgaer vs Rybka  0-1382006Copa Entel ,B51 Sicilian, Canal-Sokolsky (Rossolimo) Attack
17. Rybka vs E Cordova  ½-½742006Copa Entel ,B25 Sicilian, Closed
18. J Alvarez Nunez vs Rybka  0-1442006Copa Entel ,C85 Ruy Lopez, Exchange Variation Doubly Deferred (DERLD)
19. Rybka vs L Rojas  1-0522006Copa Entel ,D90 Grunfeld
20. Zor Champ vs Rybka 1-0872006CSS/Pal Freestyle Tourney Final (45+5)B92 Sicilian, Najdorf, Opocensky Variation
21. Ant vs Rybka 0-13420066th International CSVN TournamentA58 Benko Gambit
22. Rybka vs Deep Gandalf 1-05720066th International CSVN TournamentC42 Petrov Defense
23. Argonaut vs Rybka 0-14220066th International CSVN TournamentB50 Sicilian
24. IsiChess vs Rybka 0-13720066th International CSVN TournamentA57 Benko Gambit
25. Rybka vs Shredder ½-½6720066th International CSVN TournamentA14 English
 page 1 of 9; games 1-25 of 213  PGN Download
  REFINE SEARCH:   White wins (1-0) | Black wins (0-1) | Draws (1/2-1/2) | Rybka wins | Rybka loses  

Kibitzer's Corner
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Premium Chessgames Member
  offramp: Thanks, <Dionyseus>! I have it working now but it is only going at about 40kN/s. Is that normal?
Premium Chessgames Member
  offramp: There is an interesting position in Shirov vs Piket, 1995.

Black played 23...Re6 which lost. Shirov says the best move was 23...Qc5 after which he would have played 24.Bg5!

click for larger view

In Fire on Board he said that no computer would ever find the move 24.Bg5; mind you, he was working with Fritz 4 for that book.

May-03-06  CapoBlanco: Dionyseus:

Instead of running a tournement with many engines I just had Rybka 1.2 play Rybka 1.1 which are clearly the strongest engines at the moment. I left them playing overnight in 4' + 2" games and Rybka 1.2 looks a bit stronger but not much so. Last time I checked Rybka 1.2 was leading with 20 wins, 17 loses and about 60 games drawn. I have watched some of the games and they seem to look at the same variations with Rybka 1.2 being slightly faster. Perhaps there are some improvements in the endgame, but I don't see much difference at this time control, between 15 and 30 elo points I would say.

Rybka 1.1 on the other hand is sginificantly stronger than the beta version.

May-03-06  TheUnkraut: Hi! I would like to know what a modern engine like rybka on actual hardware says to the famous game topalov-shirov (D85, 1998). Does it find the brilliant move 47. -bh3!! ? On my old hardware, my pre-historic fritz is unable to understand that. Do modern engines on 3 gigahertz-hardware get it? I think, with enough hashtables they should....
May-03-06  LoFarkas: <TheUnkraut> After 10 minutes, CM 9000 on a 2,4 GHz PC thinks Bh3 only draws:( It prefers Be4 and some other move I forget now. After forcing Bh3, it suggests the text moves but it only dawns on it a couple of moves later that black is winning.
May-03-06  notyetagm: <sharpnova: Bxh6 is a bit faster than Rxc6.. <notyetagm> is clearly of lower chess calibre than the rest of us.>

Yes, I am a patzer because I agree with Naiditsch that ♖x♘! is a better move against a human opponent because it has more shock value than just ♗x♙!. Clearly Naiditsch and I are in the same class.

But what does Naiditsch know? After all, he only won the Dortmund tournament last year ahead of the two world champions, Topalov and Kramnik.

May-03-06  TheUnkraut: (Lofarkas) Thx for trying out! Its really an extremely hard position for a computer. Maybe the strongest engines with a reserved minimum of 1 gigabyte hashtables might solve this on infinite modus. The problem is that move Be4-no machine will instead give away material in a seemingly won position as long as it doesnt know about the result in the later endgame.
May-03-06  ganstaman: I have a possibly semi-interesting Rybka question. The other day, I was playing a game against another person and got into something similar to the following position:

click for larger view

I was white, and I was fairly certain I could draw. Black thought he had a chance, and so we played it out (it is somewhat interesting to play for a while). I think black needs to sac his rook for white's bishop and pawn, but anytime he sets that up white's king is able to get into the corner and pull off a draw. In the end, we were still undecided, so I ran the position through Rybka v1.0 Beta.w32.

The analysis took 2 seconds to get to 61 depth, and declared it a draw with this line: Kb2c2 Rd6h6 Kc2b3 Rh6e6 Kb3c2 Re6f6 Bb5d7 Rf6f3 Bd7e8 Rf3c3+

So I then played 1. Kc2 and ran the analysis again. This time, I got in 05:41, depth 29, a score of +3.43 for black with the line: Rd6h6 Kc2b3 Rh6e6 Kb3c2 Re6f6 Bb5d7 Rf6f3 Bd7e8 Rf3c3+ Kc2d2

How can it evaluate a score of 0, and then when I play the move it evaluates a score of -3.43? Also, when I played out its moves, I didn't really see black making progress. Can anyone explain Rybka's behavior? Does anyone know if this definitely is a draw or a win for black?

By the way, in case you need a pgn of a game that leads to that position, here's what I came up with (it's not the actual game, don't worry):

[Event "GCS"]
[Site "GCS"]
[Date "2006.05.03"]
[White "drawer"]
[Black "winner"]
[Result ""]
[WhiteElo "200"]
[BlackElo "2000"]
[TimeControl "0+0"]

1. e4 e5 2. Qg4 Qf6 3. Qxg7 Qxf2+ 4. Kd1 Qxg1 5. c4 Qxh1 6. Qxh8 Qxh2 7. Qxh7 Qxg2 8. Qxg8 Qxe4 9. Qxf7+ Kd8 10. a4 c6 11. Qxf8+ Kc7 12. Qxc8+ Kb6 13. Qxb8 Qxc4 14. Qxe5 a5 15. Nc3 Qxc3 16. Bb5 Qxb2 17. Qc7+ Kc5 18. Qxb7 Qxa1 19. Qxd7 Qxc1+ 20. Ke2 Qxd2+ 21. Kxd2 Rf8 22. Qxc6+ Kb4 23. Ke3 Rf6 24. Qc3+ Kxc3 25. Ke2 Rd6 26. Ke3 Rc6 27. Ke2 Kd4 28. Kd2 Rd6 29. Kc2 Kc5 30. Kb2 Kd4

Premium Chessgames Member
  percyblakeney: <it's not the actual game, don't worry>

It's a newly discovered gamescore from a match between Angermann and Warren :-)

May-03-06  sharpnova: <notyetagm>

<Clearly Naiditsch and I are in the same class.> if you're refering to the fact that you're both weaker and less efficient than Rybka, then yes my friend :) you are quite correct :)

<But what does Naiditsch know?>

vastly more than you and vastly less than rybka.

oh ya and.. Bxh6 has a lot more shock value than just sacrificing the exchange.

i'm sure naiditsch would agree :)

May-03-06  sharpnova: anyone else out there agree that shock value isn't ALWAYWS a cut and dried excuse for playing a weaker move?

aside from naiditsch i'm sure a lot of you agree :)

<notyetagm and never will be one> has some serious learning to do. feel free to email me at for some lessons. we'll start with the basics like the relative values of the pieces.

May-03-06  Sydro: <ganstaman>I think it says 0.00 because there was a possibility for white to get draw by repetion. When you played Kc2 try the move ...Kc5 and it should say 0.00 again.
Premium Chessgames Member
  THE pawn: As I was told previously, I downloaded Chessbase interface to input in the Rybka 1.0 version a opening explorer. For one reason or another, Chessbase doesn't work. But in any way, let's suppose I play again against chessmaster 9k and this time, I play rybka's first 15 moves taken from various opening explorers and databases, it still loses against chessmaster. Does this mean Rybka 1.0 is weaker than 2500? Or is it just my version that has a glitch or is corrupted. Can someone enlighten me on this? thx.
Premium Chessgames Member
  Dionyseus: <The Pawn> Rybka 1.0 beta is significantly stronger than CM. It must be Arena that's causing it to play weaker. I never use Arena, I use Fritz 9 interface.
May-03-06  notyetagm: <sharpnova: ... we'll start with the basics like the relative values of the pieces.>

You might want to do some learning yourself before giving those lessons.

One of the keys to advancing your chess understanding is learning just how meaningless the phrase "relative values of the pieces" really is.

Go read GM Jonathan Rowson's new book if you doubt this.

May-03-06  notyetagm: <sharpnova: oh ya and.. Bxh6 has a lot more shock value than just sacrificing the exchange.

i'm sure naiditsch would agree :)>

Naiditsch would agree, by choosing not to play it? You have thrown logic right out the window.

Premium Chessgames Member
  THE pawn: <Dionyseus> Thx for the feedback. That makes sense. Too bad I do not have fritz.

Any suggestions on a better interface? (downloadable, cheap etc.)

Premium Chessgames Member
  Dionyseus: <The Pawn> Sorry, i've only used chessbase product interfaces such as Shredder and Fritz. My suggestion would be to purchase a used copy of Chessbase Fritz 9 or Shredder 8 on ebay.

Just to demonstrate how much more powerful Rybka 1.0 Beta is than CM, here's a quick game I just did between it and Chessmaster 10 (don't have 9, but 10 should be stronger than 9 anyways) :

[Event "Blitz:10'"]
[White "Rybka 1.0 Beta 32-bit"]
[Black "Chessmaster 10"]
[Result "1-0"]
[PlyCount "89"]

1. Nf3 Nf6 2. g3 b6 3. c4 Bb7 4. Bg2 e6 5. d4
Be7 6. O-O O-O 7. Re1 c5 8. d5 exd5 9. Nh4 Ne4 10. cxd5 Nd6 11. Bf4 f5 12. Na3 g5 13. Bxd6 Bxd6 14. Nc4 Bxg3 15. hxg3 gxh4 16. Qb3 d6 17. Qe3 Kh8 18. Qf4 hxg3 19. Nxd6 gxf2+ 20. Kxf2 Ba6 21. Qe5+ Qf6 22. Qxf6+ Rxf6 23. Ne8 Nd7 24. Nc7 Bb7 25. Nxa8 Bxa8 26. Rad1 b5 27. Bf3 Ra6 28. d6 Be4 29. Bxe4 fxe4 30. Rg1 Rxa2 31. Ra1 Ra4 32. Rxa4 bxa4 33. Ke3 Nf6 34. Kf4 c4 35. Ke5 Nd7+ 36. Ke6 Nc5+ 37. Kf7 h6 38. Rg8+ Kh7 39. Rg7+ Kh8 40. Kf6 e3 41. Rc7 Ne4+ 42. Kg6 Nxd6 43. Rxa7 Nc8 44. Ra8 a3 45. Rxc8# 1-0

Premium Chessgames Member
  THE pawn: Wow!


impressive. Thanks!

May-04-06  notyetagm: Rybka eval please for the following position, from N Miezis vs Adianto, 2000, with White to play after 24 ... ♖xd2:

click for larger view

Black (Adianto) has just played the excellent <petite combination> 22 ... ♖xc3! 23 bxc3 ♘f3+ 24 ♗xf3 ♖xd2 to obtain a huge positional advantage: 1) two bishops, including a monstrous unopposed dark-squared b6-bishop 2) 7th-rank d2-rook 3) weak White pawns everywhere (f2-, h3-, a3-, and c3-pawns).

I'd like to know how much of a material advantage Rybka thinks this positional advantage is worth.

Black went on to win easily from this position. Just eight moves later he transformed this materially-level superior position into a healthy three-pawn advantage.

A tremendous positional display by Adianto, recalling the ease with which Capablanca used to positionally crush his opponents.

Premium Chessgames Member
  Dionyseus: <notyetagm> Rybka 1.12c says:

0 seconds: -1.46 depth 9
2 seconds: -1.51 depth 10
5 seconds: -1.72 depth 12
22 seconds: -1.64 depth 14
99 seconds: -2.12 depth 17
2m:28s: -1.52 depth 18
4m:22s: -1.61 depth 20
6m:56s: -1.64 depth 21
11m:53s: -1.60 depth 22
52m:13s: -1.62 depth 25
1h:40m:20s: -1.70 depth 26

Suggested line:
25.Re2 Bd7 26.Qb3 Qxb3 27.Nxb3 Rd3 28.Kg2 Bxh3+ 29.Kxh3 Rxf3 30.Kg2 Rxc3 31.Rb2 Bc7 (-1.70) Depth: 26 01:40:20 475442kN

May-05-06  notyetagm: <Dionyseus> Thanks.

So Rybka sees almost a two pawn advantage for Black in this even material position.

May-05-06  hitman84: Rybka analysis for the following positions please..
I'd be pleased if you could post the best line Rybka sees..

Deep Blue - Hamann,Svend 0-1 Copenagen 1993

click for larger view

White to move.

Bent Larsen - Deep Blue 1-0 Copenhagen 1993

click for larger view

White to move.

Kasparov - Deep Blue 1-0 Philadelphia 1996

click for larger view

Black to move.

Kortchnoi - Short 0-1 Koop Tjuchem 1996

click for larger view

Black to move.

Deep Blue - Kasparov 1-0 New York 1997

click for larger view

White to move.

Beliavsky,Alexander - Short 1-0 FIDE-WCH 1997

click for larger view

White to move.

Mc Donald - Wells Peter,K 0-1 London 1998

click for larger view

Black to move.

Ostenstad,Berge - Fedorov Alexie

click for larger view

Black to move.

May-05-06  hitman84: Bologon - Kasimdzhanov 1-0 Pamplona 2002

click for larger view

White to move.

Boris Alterman - Comp Sjeng 0-1 Maastricht 2002

click for larger view

Black to move.

Beutel,Jens/Comp fritz 7 - Anand,V/Comp Fritz 7 0-1 Mainz 2002

click for larger view

Black to move.

Anand,V/Comp Fritz 7 - Beutel,Jens/Comp fritz 7 1-0 Mainz 2002

click for larger view

White to move.

Alexander shabolov - Crafty 1-0 1996

click for larger view

White to move.

Premium Chessgames Member
  Dionyseus: <Hitman84> On the first one, Rybka wants to play Ne4 after 18 seconds. After 1 minute the evaluation was +1.05 and depth 17, and after 9 minutes the eval was +1.39 and depth 21. 1.Ne4 Rxb3 2.Rxb3 Nxb3 3.c5 Nd4 4.c6 Nxc6 5.dxc6 Rc7 6.Ra8 Rxc6 7.Rxa3 f5 (1.41) Depth: 22 00:18:13 107335kN, tb=5

Deep Blue instead chose 34.Rf8 Rxb3 35.Rxb3 Nxb3 36.Ne4 f5 37.Nd6 Nc1 38.Rxf5 Nxa2 39.Rxe5???? Instead of Rxe5 white can force a draw with 39.Rf3 Nb4 40.Rg3+ Kh5 41.Rh3+ Kg6 42.Rg3+ Kf6 43.Rf3+ and notice that black cannot go to Ke7 because of the fork threat Nc8+.

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