Thursday, June 21, 2018

Season 12 superfinal, games 1-8

This season's superfinal is between Stockfish and Komodo.

After 8 games the engines are tied 1-1 with 6 draws.

The first opening of the season was a King's Gambit. In game 1.1 evals started close to 0 with a small advantage to Komodo. Komodo gave the pawn back, and although Stockfish's king was uncastled and exposed it seemed relatively safe. Evals started to increase as Komodo pushed pawns on both sides, the white king walked towards the corner and trapped its own rook.

Stockfish moved the g pawn to free its rook, exposing its king further. Evals were over 2 after Komodo gave a rook for a bishop, it got the material back a few moves later and the game reached a QRB vs QRB position.

Material was equal but the white king was too vulnerable. Komodo gave 2 pawns and opened a file for its rook, a mate threat forced Stockfish to lose a rook for a bishop.

The game was soon adjudicated, Komodo was about to exchange queens for the win.

In the reverse game Stockfish kept the negative eval around 0.8 from the start. It was a pawn up but did not attack the exposed white king. Komodo exchanged pieces and on move 30 the game reached a RRB vs RRB position. Evals came down and Komodo held the draw. Komodo wins the first minimatch.

Stockfish started game 2.1 with evals around 1. Komodo's eval dropped close to 0 by move 20 while Stockfish remained hopeful. It gave a rook for a bishop, and its strong bishop pair attacked the exposed black king. Komodo traded a knight for one of the bishops and evals dropped to 0. The game ended in a drawn B vs R tablebase position (6-man, first time it is used in TCEC).
In the reverse game the center was locked, there were long pawn lines across the board and very few exchanges. Stockfish had more space on the king side and its eval turned negative. For many moves Stockfish planned to open the king side and attack, its eval constant at 1 while Komodo's eval was 0. The attack never came and the game ended in a 50 move draw.

Stockfish started game 3.1 with an eval close to 1 while Komodo's eval stayed close to 0. The black king was uncastled and Stockfish dominated the dark squares on the king side. However, Komodo kept its pawn line intact and strong and Stockfish did not find a way in.

Evals started to jump when Stockfish played g4 and made a small hole in the pawn line on the king side. Komodo's pieces had no access to the king side, and Komodo tried to counter on the queen side. The evals of both engines implied the end was near.

Stockfish sacrificed a knight to open the king side completely. The game reached a QR vs QRN position, Stockfish with an advanced king side passer and the black king under threat. Adjudication came a few moves later. 

In the reverse game 3.2 Komodo had an eval advantage from the start. It did not sttack the king side, the pawn lines stablized and the engines started to shuffle on move 20. On move 52 Stockfish opened the king side, the game reached a QRR vs QRR position and the evals quickly dropped to 0 ending the game with a draw. Stockfish wins its first minimatch and equalizes the score.

Stockfish was up a pawn with eval over 1 at the start of game 4.1. Komodo exchanged pieces until only QR vs QR remained on move 29. Evals stayed constant for a long while, Stockfish had two passers that weren't strong enough. Eventually the game reached a drawn rook ending. In game 4.2 Stockfish's eval was 0 from move 20. The engines gradually exchanged pieces and Komodo's eval came down as well. The game reached a drawn rook ending, like the previous game.

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