Tuesday, October 24, 2017

Season 10, stage 1, rounds 7-9

Table after 9 rounds:

The draw rate is 41/108 (38%). This appears to be quite low but when restricting to games by engines in the current top 9 the draw rate becomes 7/13(54%). the difference in playing strength increases the number of decisive games.

Stockfish and Komodo are a class of their own so far. Houdini is third but only 0.5 points above the group of engines fighting hard to qualify. Texel and Wasp dropped in the ranking while Gull joined the leaders. Bobcat seems to be performing better than expected, but keep in mind it got a point free off an Arasan crash. For Rybka, Hannibal and Nirvana the chances of qualification for stage 2 look slim.

Some of the game highlights:

Rybka - Chiron: Chiron took over the game from the start, with increasing negative evals. After the position opened a little Chiron sacrificed a pawn that later turned into a R vs BN imbalance. With Rybka's king sealed off the extra piece was enough to capture three more pawns and win.

Wasp - Fruit: After 40 moves the game seemed to be heading for a long draw, a closed position and shuffling moves. Wasp captured a pawn allowing Fruit to close in on its king, and after a few exchanges Fruit was clearly in control. The game reached a RN vs RN ending and Fruit's passed pawns forced Wasp to lose material and the game. Quite a surprise, Wasp was doing well and for low rated Fruit this is very good result.

Andscacs - Houdini: Houdini equalized after the opening but could not do better than that. Andscacs played very solidly, reaching a RB vs RB ending and a draw.

Arasan - Texel: Surprisingly Arasan came out in front after the opening. The evals continued to increase, Texel lost its queen side pawns and Arasan was two pawns up. Texel had to lose a piece to stop the white pawns, giving Arasan a winning position. Another big surprise (at least for me), though Arasan has shown it can play well on occasion.

Stockfish - Fizbo: Fizbo sacrificed a bishop but the compensation it got was not enough and Stockfish started to attack. Fizbo tried to build a fortress but Stockfish found a way in. When the game was adjudicated is a QRN vs QR position the win was not clear to me, the PV shows how Stockfish can avoid checks, keep the black king away and win a pawn.

Chiron - Fire: Evals remained close to zero the whole game. The engines exchanged pieces until reaching a drawn rook ending.

Jonny - Rybka: Jonny's eval is always too optimistic, but when it got over 1.5 after 40 moves there seemed to be a real advantage for Jonny. The material was even with many pieces on the board, Rybka was defending its weak pawns with little room to move. After exchanging a pair of rooks Jonny found a way to penetrate Rybka's lines and captured two pawns. The win was straightforward.

Hannibal - Ginkgo: Hannibal went for a R vs NN imbalance and Ginkgo's eval showed it was happy about this. The game reached a QR vs QNN position, after several moves with no eval change Hannibal made two moves Ginkgo considered as blunders and the evals took off. Ginkgo picked up two pawns and exchanged queens to reach a won R vs NN position.

Fire - Jonny: Jonny was optimistic as always after the opening, but when the game became static Fire shuffled pieces better and its evals increased above . At the right moment Fire opened up the king side and Jonny had to give Q for BB to escape. The material was enough for Fire to win.

Laser - Chiron: After many exchanges the game reached a RB vs RB position with opposite color bishops. Almost all pawns were exchanged and Chiron was left with one passer. The evals from both engines suggested a win for Chiron but Laser managed to hold the 7-man position, it was willing to give its bishop for the pawn to get a drawn tablebase position. A rare draw for Laser.

Fizbo - Vajolet2: Another crash for Fizbo, after only 6 moves.

Wasp - Stockfish: After 20 moves the evals were still close to 0. Stockfish gave two pawns and took over the center. Then a Wasp blunder let Stockfish start a combination where it gave Q for RBB. Stockfish's eval was over 6 in five moves, it used the rook to block the white passers and a BBN trio to control the board, both for defense and for attack. The position was still complicated when the game was adjudicated, the PV indicated that Wasp was about to lose its queen.

Komodo - Texel: Queens were off the board early in the game and by move 23 only RBN vs RBN were left. Komodo's eval started to increase, after it captured two pawns and exchanged rooks the eval was over 1.5. For a while there was no progress but after Texel exchanged the knights Komodo saw a win. In an opposite color bishops ending it was three pawns up with a pawn majority on both sides of the board. Once the white king penetrated the pawn line it was all over.

Featured game: Nirvana - Komodo
Stage 1, round 8
link to game on TCEC

What a game this was!

After 31 moves Nirvana was up an exchange in a closed QRR vs QRB position.

The evals were at 0 and the engines started shuffling. Komodo had an extra pawn and after a few pawn exchanges it became a passer.

Evals were a little in favor of Komodo but with no pawn moves the 50-move draw was getting close. With 7 moves left Nirvana took the passer, resetting the counter, and still the evals were close to 0. Then suddenly Komodo's eval shouted "blunder!" on move 152.

Through attacks on the exposed white king Komodo was able to win a rook and exchange the remaining rook pair.

Nirvana's queen had to protect the b3 pawn. Komodo's queen danced around the white king until it could capture the e4 pawn and force a queen exchange. Here the game was adjudicated. This is an example of what Komodo is famous for, winning games that look like dead draws. 

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