The 29th Dutch Open Computer Chess Championship was held in Leiden this past weekend and Rybka won ahead of Deep Sjeng and The Baron.

Thanks to the organizers for another successful event and to the guys on our team for their hard work. Our team was:

Operator: Hans van der Zijden
Hardware: Lukas Cimiotti
Opening book: Jiří Dufek
Engine: Vasik Rajlich

Lukas has continued working on his cluster, which now contains 9 Nehalem 8-core machines running at speeds ranging from 2.93 to 3.33 GHz. For the first time, we were fully ready several days before the tournament and had no major problems during the event. This project has been a lot of work but also a great succes and quite some fun. The next steps are to clean up a few things and to configure and optimize some of the algorithm's parameters. We also hope that there will be some freestyle events in the next couple of months so that we can showcase what we have done.

Jiří again handled our opening book. He's adapted himself very quickly to the unique requirements of the situation: outbook the Deep Sjeng team, the main tournament threat for already some time and especially now, and avoid drawish lines with both colors in the remaining games. Jiří has tackled the drawing issue in a moderate way, manually eliminating long well-treaded variations but still playing mostly mainstream openings. He also changed his testing methods to include a bigger variety of opening books and engines, to better-simulate the tournament conditions. Our opening play was again a big success - the two primary goals were clearly reached and as a nice bonus two games were practically won by the book on the last day.

Hans was again our operator and was joined on the last day by Jeroen Noomen, who made a visit to the tournament as his computer chess sabbatical winds down.

Despite Rybka playing reasonably well this time, the tournament was again exciting as Deep Sjeng ripped through the rest of the field and finished half a point behind us and two points clear of third place. Tournament play comes down to hardware & parallelization, book preparation, and single-CPU engine strength, and the Deep Sjeng team seems to have checked all three boxes and will likely remain a force for the near future.

The tournament web site is here: http://www.computerschaak.nl/
The tournament forum thread is here: http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=12928
Jiri's opening report can be found here.
All games can be found in our updated Rybka Cluster Base
Gian-Carlo's thread about Deep Sjeng can be found here: http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=12969

Vas

I have more time before Leiden tournament and during preparation i totally changed philosophy of book. I disabled all long lines in book where exists risk of draw and added new openings which offers lot of space for playing – main aim was not testing quality of opponents book. During preparation helped me lot of chess literatury again – books by Quality Chess and Gambit books where I found, analysed and improved lot of lines.

I changed too testing phase – this time I tested only little on Playchess, but much more I tested against different engines and different openings books (which are freely available on the internet) which offers wide spectrum of openings for testing. It was tested in over 700 games (in 10 periods, every period took 2-3 days) when Rybka 3 scored approx. 76%. After finishing every period I checked all games and prepared innovation in lines, where I wasn’t happy.

Round  1: Hermann–Rybka

I didn’t predict that my “secret” opening will be unhide in the first round. Tango (3..Nc6!? – and Palliser book about it) worked very well. Last book move was 10..Nd7
1. Nf3 Nf6 2. c4 e6 3. d4 Nc6 4. a3 d6 5. Nc3 g6 6. e4 Bg7 7. h3 O-O 8. Bg5 h6 9. Be3 Re8 10. Bd3 Nd7

[D]

With score about +0.36 for white after 11.0-0. What is more important – on the board will be kind of King’s Indian defence, which engines plays pretty bad. Only 5 moves later score was lightly positive for black and  after 20....bxa5 score jumped was very close to +1 for Rybka. Games was finished with very nice attack by Rybka.

Round  3: Sjeng-Rybka

I was very surprised with this pairings, because this game was decisive for all tournament.
1.e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 a6 5. Nc3 Qc7 6. Be2 b5 7. O-O Bb7 8. Re1 Nc6 9. Nxc6 dxc6 10. e5 Rd8 11. Bd3 c5 12. Qe2 c4 13. Be4 Bxe4 14. Qxe4 Ne7 15. Be3 b4 (last book move, somewhere about 0.00)

[D]

Its interesting that GCP told me, that Sjeng was out of book after 10..Rd8, because I think that Erdo knows this line up to 14.Qxe4
In this game there were three openings milestones: first is 12.Qe2 – there are others possibilities as 12.Qh5 , 12.Qg4 or 12. Bg5.  I think that after all black hold equality but he need some precise moves. Second one will be hidden for this moment and will be uncovered lately :-). Third one is 16.Nd1 (16.Ne2 was played before).
Very interesting about this line is how different engines hadle this variation – and answer is: simply bad. Engines very often overestimated  white position which leads lately to catastrophe. Sjeng played not so his best and after piece sacrifice for only 2 pawns and few checks games was over.

Round 4: Rybka-Hansdampf

In this game Hansdampg played Nimzo-indian and played very well. Last book move was 10.g3
1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. f3 d5 5. a3 Bxc3+ 6. bxc3 c5 7. cxd5 Nxd5 8.dxc5 f5 9. Qc2 f4 10. g3

[D]
I must say that I was surprised, that Rybka didn’t choose after 10..Nc6 nor 11.Qd3 neither 11.e4 but 11.Nh3!?. After this position became quite complicated but after 16.Nd6 (+0.34) Rybka started like it:

[D]

Black greedy took rook (16..Bxb1) and  immediately score jumped to +1.16 after 17.Qxd5. After this black position was worse and worse and black resign at move 42

Round 5: Rybka-Pandix

There is not much what say – after opening Rybka took exchange and won game in endgame.
1.d4 Nf6 2. c4 e6 3. Nf3 d5 4. g3 dxc4 5. Bg2 Bb4+ 6. Bd2 a5 7. O-O O-O 8. Bg5 (last book move)

[D]

Pandix played 8..Nbd7 which looks as inaccuracy (8..Nc6 is more common) and after 9. Qc1 h6 10. Bxf6 Nxf6 11. Qxc4 b6 12. a3 Be7 13. Ne5 Ba6 14. Qc2 Qxd4 15. Nc6 Qc5 16. Nxe7+ Qxe7 17. Bxa8 Rxa8

[D]

Rybka won exchange and safely converted advantage to win.

Round 6: Ktulu-Rybka

Ktulu is known me as very good engame player and dangerous engine (probably Sjeng team can talk about it for Sundays game).
1.e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 Nc6 5. Nc3 Qc7 6. Be3 a6 7. Qd2 Nf6 8.O-O-O Be7 9. f3 b5 10. Kb1 Ne5 11. g4 O-O 12. g5 Nh5 13. f4 Ng4 14. e5 b4 15.Ne4 Bb7 16. Rg1 (16.Bg2!?) 16..Bxe4  (last book move, score about +0.00 after 17.Rxg4 d6)

[D]

This line is very complicated and maybe 8..Be7 will in the future replace now more popular (and long time mentioned as only move) 8..Bb4. After 17.Rxg4 we have very lively and interesting position on the board.  However Ktulu didn’t understand his position and lost game pretty quickly and resigned with piece up but under matting attack.

[D]
0-1

Round 7: Rybka-Baron

Baron played very well in tournament and very well against us.

1. d4 d5 2. c4 dxc4 3. e3 e5 4. Bxc4 exd4 5. exd4 Bd6 6. Nf3 Nf6 7. O-O O-O 8.
h3 Nc6 9. Nc3 h6 10. Qc2 (last book move, 10..Na5 11.Bd3 around +0.3)

[D]

Baron had prepared 3 moves more in the book. Arising position resembles Russian defence and give small advantage for white. During all game Baron defended very well (with help of moves which I dislike – 17..f5 for example) and in spite of score climbed up to +0.65 for Rybka  during game,  on the board remain few pieces and game ended in a draw. My congratulions to Baron team (and Arturo Ochoa for his book)

Round 8: Joker-Rybka

Joker played all tournament without book and this time he hadn’t any chance against Rybka.
1.e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 Nc6 5. Nb5 d6 6. Bf4 e5 7. Bg5? Qxg5 8.Nc7+ Kd8 9. Nxa8 Nf6 10. Nc3 Nd4 -/+

[D]

Rybka very quickly over +1 and white could resign every time, but he played until move 56.

Round 9: Rybka-The King

1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. g3 dxc4 5. Bg2 c5 6. O-O Nc6 7. Qa4 cxd4 8.
Nxd4 Qxd4 9. Bxc6+ Bd7 10. Rd1 Qxd1+ 11. Qxd1 Bxc6 12. Nd2 b5 13. a4 Be7 14.
axb5 Bxb5 15. Nxc4 (about +1)

[D]

During this game I was pretty nervous. The King chose line, which leads to small material advantage with drawing chance for black. I think,thatthis position is quit difficult for engine-only games and The King played weakly endgame than middlegame in this tournament.
The  King missed after 15… O-O 16. b3 Rfd8 17. Qc2 Rdc8 18. Ba3 Bxa3 19. Rxa3 h6 20.
Qb2 

[D]

possibility exchange remaining queens pawns with  20..Bxc4 21.bxc4 Rxc4 22.Rxa7 or 22.Qb7 and 23.Rxa7 – when its not clear how to simple enlarge white advantage (of course – kingside pawn storm is only possibility). After that black position quickly collapsed mainly with help of 34..a4? – after this move passed b-pawn was unstoppable.

Summary – I think that opening was quite succesfull for Rybka. We didn’t get worse position after opening and Rybka had every chance show her playing strength. New openings works very well and suited Rybka’s playing style. Of course, there are moments, which are important for future development of book – games with Hansdampf and Baron come on mind and question if is Catalan playable for win after game with The King :-). Last but not least i thanks and congratulate to Lukas and Vasik for their beast and fourth Leiden-win in a row :-). Congratulions too second Sjeng team and third Baron team too for excellent tournament.