Monday, October 30, 2017

Season 10, stage 1, rounds 13-15

Table after 15 rounds:

Stockfish and Komodo lead the table, with equal points after Komodo closed the 0.5 gap. They drew their head-to-head match. Houdini and Andscacs are next, both still unbeaten this stage. Houdini has yet to play Stockfish, the remaining game within the top 4 group - all the others have been draws.
Ginkgo remains in fifth 1.5 points above 9th place, so with very good qualifying chances. Fighting for the three last spots are Gull, Booot, Fire, Chiron and Hannibal. I don't believe that Jonny or Bobcat will make it, a full point behind with 8 rounds to go. 

Some of the game highlights:

Fire - Nirvana: Fire had a small eval advantage from the opening. After most pieces were exchanged only RB vs RN remained on move 29 and a draw was agreed several moves later. Not a good result for Fire.

Wasp - Hannibal: Wasp had two pishops and Hannibal two knights in a closed position. There were no captures starting from move 25, only shuffles and a few pawn moves. Then in a series of exchanges the position opened up a little but only B vs N remained. The evals favored Hannibal but for a long time the engines were stuck. Instead of waiting for the 50-move draw Wasp made a few pawn moves, lost a pawn and then Hannibal's knight found a way past the pawn line, game over. Looked like a bad blunder by Wasp, almost no chance of qualifying now.

Gull - Jonny: Jonny blundered the opening terribly, allowing Gull to open the h file with a crushing attack on the black king. The game was over in 27 moves. Great for Gull, not so good for Jonny though it is still in the fight for the top 8.

Bobcat - Chiron: Bobcat sacrificed a piece to expose the black king and then drew the game with perpetual check. This draw keeps both engines in the qualification race.

Arasan - Stockfish: Stockfish sacrificed two pawns, and only got a quick repetition draw. A rare draw for Stockfish, Komodo with a chance to catch up at the top. Good game for Arasan.

Houdini - Booot: See my live blog for this game. Houdini had an eval advantage from the start, both engines had the habit of not showing their PVs, but what they did show looked like a draw with opposite color bishops. On move 28 Booot blundered and allowed Houdini to capture the black a pawn. Houdini's eval jumped to around 2. Houdini's a pawn became very strong and Booot had to work hard to stop it. Eventually it lost a piece and the game. Houdini back to 3rd in the table, Booot still 0.5 points from 8th position but will have to get wins to get there.

Chiron - Andscacs: The game developed into an open position with a lot of room for both engines' pieces. Andscacs gave a rook for a bishop and pawns, exposing the white king for attack. Chiron countered with an attack on the black king, leading to exchanging pieces and a R vs B ending. The evals fell to zero and the game ended a draw in a curious position, each engine with a pair of connected passers defended by the opponent's king.

Jonny - Bobcat: Jonny's king was exposed in the center while Bobcat's pieces on the king side were trapped and ineffective. Bobcat captured a free pawn, not seeing the danger to its king, and Jonny's eval jumped over 5. Within a few moves the black king was close to being mated, and Bobcat lost a piece to stay alive, leading to a won RN vs B ending for Jonny. A step back for Bobcat, Jonny compensates for its previous loss and joins the race again.

Hannibal - Gull: Hannibal had a pawn majority on the queen side that turned into an advanced passer. Gull exchanged pieces and won an exchange to reduce to a QN vs QR ending. While Gull prevented the queening of the passer Hannibal found a perpetual check draw.

Ginkgo - Wasp: Wasp gave a knight for pawns, and after several exchanges only BNN vs BN were left, Wasp with a connected pair of passers. Ginkgo was able to stop the passers, leaving it with one pawn and a wrong colored bishop. Ginkgo thought it was winning, Wasp knew it was a draw.

Fizbo - Fire: Fizbo had a pawn majority on the queen side and Fire was better in the center, Fire saw nothing while Fizbo's eval was slightly positive. Fizbo added pieces to the queen side and its eval jumped to around 2, Fire's eval also jumped but still below 1, it seemed probable that Fire could hold since it is generally stronger. The engines liquidated the queen side, leaving one white advanced passer in a QRB vs QRN position. The engines exchanged pieces so that only queens remained and the incredible happened - Fizbo outplayed Fire in a queen ending, considered (by me at least) to be one of the most complicated of endings. This result probably won't help Fizbo to qualify but it may hurt Fire.

Gull - Ginkgo: The position opened up with a long series of exchanges that resulted in a knight ending. It then took a very long time for Gull to lower its eval and allow draw adjudication. Both engines still safe in the top 8.

Bobcat - Hannibal: Many exchanges after the opening led to a bishop ending, and this time Bobcat was the one that delayed adjudication for more than 90 moves. A draw result not good for both engines, both below the qualification bar.

Andscacs - Jonny: Andscacs had an eval advantage from the start. There were several exchanges that resulted in an unusual imbalance RRBB vs QNPP and evals over 1.5. Both kings were exposed and Jonny used every opportunity to give checks with its queen and try to fork and capture white pieces. For a while the evals remained constant, but eventually Andscacs found the right piece configuration to threaten Jonny's king while avoiding its queen. Another loss for Jonny, in danger of losing touch with the leaders.

Arasan - Chiron: Chiron was never in danger but couldn't get any advantage either. In a QRR vs QRR position Arasan had a passer that forced Chiron to draw by perpetual check. A missed chance for Chiron against one of the lower ranked engines.

Houdini - Fruit: The opening was a variant of the king's gambit, Fruit was ahead on eval most of the game and after most pieces were exchanged Houdini could not do better than perpetual check. Houdini lost a chance to get closer to Stockfish and Komodo.

Featured game: Komodo - Stockfish
Stage 1, round 15
link to game on TCEC

The two table leaders played each other for the first time this season, and everyone was curious to get a first idea of who is stronger. The chat was unusually crowded with many fans of the engines following the game closely.

The game was not very exciting after the opening, evals stayed close to zero. For a while Stockfish thought it had a small advantage but it stayed small and was quickly gone. Komodo concentrated forces on the open d file, Stockfish had enough counter-threats to hold the position.

A few moves later a long line apperared in both the engines' PVs, full of exchanges and resulting in a RB vs RB position that looked very drawish. As they started playing out this line Komodo startled everyone with a 0.7 eval. It found a change in the line it thought was much better. Stockfish's eval stayed at 0 as it continued to play until the diverging point of the two lines.

Everyone held their breaths to see how Stockfish would react. After a long think the answer Stockfish gave was - Komodo has a point !! The new Stockfish eval was 0.84, identical to Komodo, and the PV also agreed with Komodo. Another case of aggressive pruning gone wrong? The engines continued with the new line, resulting in a RBB vs RBB position. Komodo was a pawn up and had two passers on the queen side, though the evals did not increase.

Although it was surprised, Stockfish handled this position easily, quickly removing the threats. Evals came down to 0 and the engines continued to exchange pawns and pieces until reaching a tablebase draw.

Komodo showed us that these two giants can still surprise one another, even if they are very hard to beat. We expect many exciting games in the next stages, with more high-level games and slower time control.

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