Those who have followed the computer chess scene for the past year or two have witnessed one of its biggest revelations – the release of Rybka. Its first beta version was released in December 2005, and in spite of the bugs and rough edges, it surpassed all other programs. Some computer chess experts, shocked by the strength of the program, needed time to adjust, before they could accept the fact that it was truly an original creation by international master Vasik Rajlich. It soon became clear that it was only a matter of time until Rybka became the World Computer Chess Champion.

Well, that time has arrived. The 15th ICGA World Computer Chess Championship (WCCC) was held in Amsterdam from June 11-18, 2007. Twelve programs fought for the title in this round robin event. The favorites, apart from Rybka, were former world champions Zappa by Anthony Cozzie, and Shredder by Stefan Meyer-Kahlen. Rybka’s games against these two formidable opponents were very interesting. The game against Zappa was drawn after Rybka built up a theoretically won endgame position. In the game against Shredder, played in the final round, Rybka had white in the poisoned pawn variation of the Sicilian Defense. Jeroen Noomen, Rybka’s opening book author, was well-prepared for the 10.e5 line, and proved that Shredder’s opening book was not up-to-date. Thus Shredder failed to compute its way through the myriads of traps and tricky lines, leading to a fifty-four move victory for Rybka. So, approximately eighteen months after its initial release, Rybka has won the WCCC title. It scored +9 =2 to finish 1 point ahead of Zappa and 2.5 points ahead of third place finisher Loop.

Vasik Rajlich.

The following dazzling game, against Diep by Vincent Diepeveen, was played in the ninth round. The comments are based on notes from Vasik Rajlich (VR), Jeroen Noomen (JN), and, of course, Rybka!

Rybka 2.3.2 – Diep

15th WCCC (9), Amsterdam 2007
Sicilian [B34]

1.e4 c5 2.Nf3 e6

I fully expected a Najdorf, but 2…e6 was played instead (JN).

3.d4 cxd4 4.Nxd4 a6 5.Nc3 b5 6.Bd3 d6 7.O-O Nf6 8.Be3 Bb7

Black’s book abruptly ended here, in the middle of a theoretical Sicilian minefield (VR).

9.f4 Nbd7 10.a3 Qc7 11.Qf3 Be7 12.Rae1 Nc5 13.Bf2 d5 14.e5 Nfe4

15.f5!!

The opening has turned out fine for White and Rybka doesn’t bother to defend against the threatened 15…Nd2. Instead, it plays the aggressive 15.f5!!, which uncorks some magnificent fireworks and puts the e5-pawn en prise in the process (JN).

The move 15.f5 is a novelty, but Rybka 2.3.2a, the version released after the world championship tournament, needed only one second to find this move. White played less aggressively in Rubinstein, Jose – Garcia, Raimundo, Mar del Plata 1962: 15.Bxe4 Nxe4 16.Nxe4 dxe4 (DJ).

15…Nd2

Diep goes for the material, but ends up in deep trouble (JN).

16.Qg4 g6

16…Nxf1!? 17.Qxg7 O-O-O 18.Bxf1 exf5 (Rybka).

17.fxe6 fxe6

I don’t know the latest theoretical variations, but Black could not navigate the complications and his position was soon lost, after only seventeen moves (VR).

17…O-O!? 18.exf7+ Rxf7 19.Bxg6 hxg6 (Rybka).

18.Ncxb5!

Diep didn’t see this coming. The remainder of the game is simply beautiful. Rybka goes a rook down, but wins everything back with heavy interest (JN).

Rybka also finds this sacrifice easily “over-the-board” (DJ).

18…Qd7

Accepting the sacrifice with 18…axb5 is hopeless after 19.Bxb5+ (DJ).

19.Nd6+ Bxd6 20.exd6 O-O

20…O-O-O!? (Rybka)

21.Bxg6!

Rybka continues sacrificing material, but the unexpected quiet move that follows (22.Nf3!) really turns this combination into something special (DJ).

21…hxg6 22.Nf3! Nxf1 23.Bxc5 Bc8 24.Ne5 Qg7 25.d7 Bxd7 26.Nxd7 Qxd7 27.Bd4 Rf7 28.Qxg6+ Rg7 29.Bxg7 1-0

A superb game, I loved it! A crushing victory in only twenty-nine moves is very rare in computer games these days (JN).

Had Diep not resigned, Rybka expected 29…Qxg7 30.Qxe6+ Qf7 31.Qg4+ Qg7 32.Qxg7+Kxg7 33.Kxf1, with three extra pawns in the rook endgame and an easy win.

Rybka Triumphant

Dagh Nielsen has compiled statistics for all nine official tournaments that Rybka has played in to date. Rybka won eight of those tournaments and shared second place in the other. Its total score is 69.5/79 (88%) with 62 wins, 15 draws and only 2 losses!

On July 6-8, 2007, Rybka won a six game match against GM Jaan Ehlvest 4.5 – 1.5. The time controls were 90+30 for Ehlvest and 45+15 for Rybka. Ehlvest played white in all six games, and Rybka was limited to a three move deep opening book, a 512MB hash size and didn’t use tablebases.

Rybka has its own busy forum, where Vasik Rajlich answers questions and discusses all things Rybka related (and unrelated, too). Also, Convekta has released a free beta version of several chess products for Nokia smartphones. They can be downloaded from the “Features and Functionality” board on the Rybka forum. One of the products, Pocket Champion, shows the planned Rybka GUI for smartphones.

Rybka 3 will be released later this year or early in 2008. Convekta is currently working on a new GUI for Rybka that will be released in unison.

In the minutes of FIDE’s Presidential Board meeting in Tallin (June 22-25) we can read that President Ilyumzhinov said that “there is also a growing interest toward computer competitions,” and he suggested the organization of another computer challenge match, between Rybka and Deep Junior in Mexico City.

Dadi Jonsson.