Wednesday, June 27, 2018

Season 12 superfinal, games 33-38

After 38 games Stockfish leads 8-4 with 26 draws. Komodo is still behind but it is fighting back. The match is not really one-sided like in season 11,  this makes it much more interesting. There are many decisive games, the draw rate is at 68%.

Evals stayed close to 0 throughout game 17.1, despite Komodo having a pawn advantage from the start. On move 20 the game reached a BN for R imbalance and evals were 0. Komodo had an advanced passer on the queen side, Stockfish broke through the king side with a knight sacrifice and ended the game with a repetition check.

In the reverse game 17.2 Stockfish was a pawn up and had a negative eval of about 0.5. Komodo locked the center and Stockfish concentrated forces on the king side. Stockfish's eval came down after Komodo exchanged pawns on the king side. Komodo then gave another pawn and created a central passer, its eval starting to increase.

The white passer on e6 could not be touched and was a constant threat. Stockfish's eval increased as Komodo took the initiative. Komodo captured the two weak pawns on the queen side and equalized material. Stockfish had no counter, it had to block the passer and had little room to move. In desperation it gave a knight for the passer. 

Komodo traded down to a QNN vs QN position.The extra piece was enough to give Komodo the win, though the game was adjudicated before the win was clear. In Komodo's PV it captured the black queen a few moves later. Komodo is fighting to stay in the match.

Stockfish's eval was about 1.5 from the start of game 18.1, a Benoni opening. Komodo's position was very cramped, Stockfish pushed pawns on the king side and opened the h file. Komodo's king was in danger while all the black pieces were on the queen side, Stockfish's eval was over 2.

Komodo's counter was a passer on the queen side. Stockfish attacked on the h file, Komodo gave two pawns in the hope that the white pawns will shield its king. The evals continued to increase all the time.

Stockfish exchanged pieces and won two more pawns. After exchanging queens the game was adjudicated, the material advantage was enough for a win.

The reverse game 18.2 developed very differently. Stockfish opened a file in the center and another on the queen side, allowing its pieces to move more freely. The engines exchanged pieces until reaching a drawn rook ending. 

Game 19.1 started with a knight sacrifice by Stockfish that opened the king side and exposed the black king. Komodo immediately gave the material back and exchanged queens. The engines continued to exchange pieces, the game reached a RB vs RN position on move 30. Evals came down but Stockfish thought it still had a small advantage. As a result the engines continued to shuffle for more than 40 moves to agree on a draw.

In the reverse game 19.2 the king side stayed intact, Komodo was a pawn down but had an eval advantage as Stockfish's king moved and could not castle. Komodo found a great square for its knight on e6, controlling a lot of black territory. The black king side rook was miserable in the corner.

Evals started to increase, Stockfish traded knights to get rid of the black knight on e6, Komodo simply moved its other knight to the same square. Komodo then opened the center and got the pawn back, its pieces were much better placed and the king side pawns were ready to march.

Stockfish was essentially playing a rook down, evals jumped quickly as Komodo attacked. After a series of exchanges only Q vs RB remained, Komodo with a central passer.

Stockfish couldn't stop the white passer without losing a piece, a win for Komodo. Komodo played this opening much better than Stockfish.

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