Thursday, October 26, 2017

Season 10, stage 1, rounds 10-12

Table after 12 rounds:

More than half of the stage is behind us, and the table starts to make sense.

Stockfish and Komodo lead the table, both with no losses, 2 draws for Stockfish, 3 for Komodo. Keep in mind that Stockfish hasn't played Komodo or Houdini yet, while Komodo and Houdini already drew their game. Houdini is third, also unbeaten but with 6 draws the gap to the leaders is significant. Next in the table is Andscacs, also unbeaten and after playing and drawing the top 3 engines. Ginkgo has the same number of points, with one loss to Stockfish. These 5 engines seem to be safe bets for finishing in the top 8.

The engines fighting for the remaining two qualification spots are Fire, Gull, Chiron, Booot, Jonny and Bobcat, with some chance also for Hannibal and Wasp. I don't think the rest of the engines have a chance to qualify based on their results so far, including Nirvana and Rybka that have a high TCEC-ELO score. Still 11 rounds to go so anything can happen.

Some of the game highlights:

Houdini - Komodo: This game was highly anticipated, one of the few games of stage 1 where the real giants play each other. Houdini had a bishop pair advantage over Komodo's knight pair but it was Komodo who was slightly ahead in eval, the knights more effective in a closed position. Komodo's fans were getting a little excited, while Houdini's PV started to show a long line that ended in a RB vs Q position. A few moves later Komodo found the line and both engines played it out. Almost immediately the evals dropped to 0 and the game was drawn. No drama in the end.

Stockfish - Gull: Gull sacrificed a pawn on move 5, Stockfish kept the pawn advantage for a long time, together with a small eval advantage. The engines exchanged pieces and the eval increased gradually. At move 27 only QRN vs QRB remained, and for a while it seemed the engines were shuffling. The evals continued to increase and when on move 55 only queens remained Stockfish's eval was over 1.5. Stockfish forced a queen exchange and the extra pawn was enough for a win. "A pawn is still a pawn..."

Hannibal - Fire: Queens were exchanged early in the game. Fire had a bishop pair but two weak pawns as well, Hannibal had a small eval advantage. Around move 40 it seemed that Fire played inaccurately, allowing Hannibal to capture two pawns together with higher evals. On the other hand Fire's bishops were strong in the open board and it had a pawn on the 2nd rank. Fire insisted it was a draw, and proved its claim when it combined the advanced pawn with a bishop to imprison a white rook in the corner.

Fire - Ginkgo: Evals were close to 0 all through the game. Fire gave a pawn early in the game. After many exchanges only QR vs QR remained, even with the extra passed pawn Ginkgo could not make progress, draw.

Laser - Hannibal: Laser seemed to be holding against Hannibal in a RB vs RB position. Hannibal had better pawn structure and a passer, but made no progress for a long time. After more than 90 moves Hannibal finally saw a way to win, or was it a Laser blunder. Once the passer reached the 2nd rank the game was over.

Bobcat - Stockfish: After 24 moves only QBN vs QBN remained with evals close to 0. Bobcat's bishop was half trapped and not very effective, evals turned to Stockfish's favor but still mostly balanced. After exchanging queens Stockfish had the initiative but progress was very slow. At move 64 Stockfish managed to capture a pawn and was clearly in front, Bobcat kept fighting for a long time and admitted defeat only after losing a second pawn 20 moves later.

Texel - Houdini: Houdini closed the center with a long pawn chain. Texel didn't see the danger to its king until it was too late. Houdini sacrificed a knight but Texel had to give it right back to try to defend its king. The attack was too strong and Texel's pieces were too far to help, a quick crush by Houdini.

Nirvana - Houdini: Houdini had the initiative and an eval advantage in a closed position. Nirvana gave a bishop for three pawns to get an attack on the black king and two passed pawns in a RN vs RBN position. Houdini quickly exchanged rooks and then both engines went after the pawns. In the end Houdini had only two pawns but they were enough in a N vs BN ending. Back-to-back wins in black for Houdini.

Stockfish - Andscacs: Stockfish thought it may have something in a RRN vs RRN closed position. The position became static and the evals came down to 0. A good result for Andscacs, no losses yet and draws against all top 3 engines. Only the second draw for Stockfish this stage.

Chiron - Gull: Chiron was a pawn up early in the game with a small eval advantage. The eval increased to about 0.9 in a RBN vs RBN position on move 41 but got no higher. The rest of the game was pawn exchanges and evals going back down, and finally a draw.

Featured game: Komodo - Booot
Stage 1, round 11
link to game on TCEC

After 22 moves Booot was a pawn up while Komodo's pieces were better and it had the initiative.

Booot gave back the pawn and exchanged pieces until only QRB vs QRB were left, relieving some of the pressure. Komodo had better pawns and an eval advantage, the question was: is that enough for a win?

Komodo attacked the black weak pawns and Booot tried hard to defend when without warning Komodo's eval jumped over 3. Booot thought it was safe exchanging everything to get a bishop ending but it missed Komodo's move 46.

Booot eval=0, Komodo eval=250, unbelievable!! The black king is too far away from the b passer and the black bishop has to go around the long way, giving Komodo too many free moves. Booot forced a bishop exchange but realized it was lost anyway.

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