Thursday, July 5, 2018

Season 12 superfinal, games 83-88

After 88 games Stockfish leads 24-7 with 57 draws. The draw rate continues to be low, now at 64.8%. There are 12 games left, Stockfish is officially the winner of TCEC season 12. Komodo's last win was in game 56, since then Stockfish is leading 12-0.

The black king moved in the game 42.1 book sequence. Stockfish castled long and 
pushed pawns on the king side. Komodo let its king side rook out through the h file, but it was almost trapped by the white pawns. 

Stockfish threatened an attack on the g file, Komodo reacted by surrounding its king with pieces. Stockfish sacrificed a pawn and opened the f file, its eval jumped over 3.

Stockfish won a rook for a bishop and after several exchanges only RRN vs RBB were left.

Stockfish soon captured the g pawn. Komodo had a bishop pair, but its king was exposed and open to the rooks attacking. The game was adjudicated, Stockfish's PV showed how Komodo could lose a piece several moves later.

Evals stayed close to 0 in the reverse game 42.2. Komodo did not open the king side, instead it attacked in front of the pawns. Stockfish used its trapped king side rook to protect the g pawn, then it sacrificed a rook and counter attacked on the queen side. The black king was in danger, Komodo chose to end the game with a perpetual check draw.

Stockfish started game 43.1 with an eval close to 1. The engines kept exchanging pieces, and the evals fell to 0 after move 30. On move 40 only RB vs Q remained, both kings were exposed and the game ended with a series of checks. In the reverse game the evals fell to 0 almost immediately. Again the engines exchanged many pieces and on move 36 only QN vs QN remained. Both engines had advanced passers, Stockfish promoted first but had to promote to a knight with check to prevent mate on its king. After exchanging queens Stockfish gave a knight to stop the white passer, leading to a knight ending and a tablebase draw.

The 44th opening was another King's Gambit variant. In game 44.1 queens were exchanged early. Komodo was a pawn up and its king uncastled, Stockfish's king was exposed in the king side. Evals were negative but never more than 0.5, Stockfish had a bishop pair advantage and evals slowly came down. Komodo had a connected pair of passers on the king side, Stockfish managed to stop them and through a series of exchanges to reduce to a rook ending and a tablebase draw.

In game 44.2 evals were negative and constantly increased from the start. The king side remained relatively intact and Stockfish castled its king. Komodo had a bishop pair, Stockfish kept its pawn advantage from the opening and managed to place a knight on g3 in front of the white king. The engines exchanged queens on move 30, Stockfish's eval approaching 2.

The pawns on the queen side were all isolated, and they were targeted by the pieces of both engines. It took 15 moves of careful planning, eventually Stockfish was able to capture one of the doubled pawns on the d file.

Stockfish started to push pawns on the king side, its king moved forward to support its pawns. Komodo reacted by exchanging pieces, and on move 58 only BB vs BN remained.

The two extra pawns were stronger than the bishop pair. Komodo gave one of its bishops for two pawns and the B vs BN ending was a win for Stockfish.

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