Thursday, November 8, 2018

Season 13 superfinal, games 87-92

After 92 games Stockfish leads 13-6 with 73 draws.
Stockfish's lead is 7 points with 8 games remaining in the superfinal.

There were only a few exchanges before move 24 in game 87. Stockfish went a pawn up and after a series of exchanges only RBN vs RBN were left. Komodo got the pawn back and the engines started to shuffle. After exchanging a pair of knights and a few pawns Stockfish was again a pawn up, the shuffling continued. Stockfish lowered its eval only when the draw counter was close to 50, and adjudication followed.

Komodo had a small eval advantage at the start of game 88. There were only a few exchanges, evals started to increase when Stockfish pushed pawns on the king side. Komodo's pieces retreated, its king's position looked solid while the black king was exposed.

Komodo gave a pawn on the queen side, then exchanged a rook for a knight and captured two black pawns on the king side. Evals increased over 1, Komodo controlled the king side and the black king looked vulnerable.

Stockfish exchanged pieces, giving back the material until only RB vs RB were left. Komodo had two passers on the king side while Stockfish had a passer on the queen side. The white rook and black bishop were trapped by pawns on the queen side, the engines could only play on the king side. 

The black rook was not strong enough to stop the pawns from advancing and the white king from infiltrating the queen side. Komodo had time to capture the black passer, it then secured its king side pawns. Stockfish opened the queen side and freed its bishop, this also freed the white rook and created another passer and a won ending for Komodo. A minimatch win for Komodo, reducing Stockfish's lead to 6 points.

Stockfish had an eval around 1 in game 89. It gave 3 pawns for a knight and opened the center, after exchanging queens evals started to come down. The engines reduced to a RB vs R ending, evals were at 0 and the game was adjudicated by the draw rule. In game 90 the center stayed closed and there were a few exchanges. The engines opened a file on the queen side and exchanged a pair of rooks, then started to shuffle. Komodo gave a knight for pawns to open the queen side and create a passer. Stockfish gave the knight back and moved its queen and a rook to the white back ranks. After a series of exchanges only QB vs QB remained, evals came down and the game was eventually adjudicated after most of the pawns were captured.

Games 91-92 started with a long 35-ply book variant of a closed Ruy Lopez. In game 91 Komodo sacrificed a knight for two pawns and opened the center. Stockfish countered by giving a rook for a bishop and opening the black king side. Komodo was ahead on material yet Stockfish's eval was close to 3.

The black king was exposed and in danger of mate, there were not enough black pieces available to defend it. Komodo gave back a rook for a bishop to remove one of the attackers. This left QNN vs QBN on the board.

Komodo's king walked to the queen side to get away from the white pieces, Stockfish captured a pawn in the process. The engines exchanged a pair of knights, evals continued to climb despite the small material difference.

The black king was still exposed to checks, this gave Stockfish extra queen moves. The h pawn started to march, Komodo couldn't stop it without losing its bishop and the game.

Game 92 was quiet, evals stayed low and the engines gradually exchanged pieces until only RN vs RB were left on move 34. Evals were 0 as the engines captured the pawns, the game ended with all the pawns gone in a tablebase draw. Stockfish extends the lead back to 7 points.

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