Sunday, November 11, 2018

Season 13 superfinal, games 93-100

Stockfish is the season 13 winner. It won the superfinal 16-6 with 78 draws.
Stockfish added 3 more wins in the last 8 games.

The engines castled in opposite directions in game 93, then pushed pawns facing their opponent's king. The black pawns on the queen side made contact with the white pawns, and this locked the queen side. Komodo opened a file on the king side and created a central passer. Stockfish captured two black pawns on the queen side and went a pawn up, while creating a queen side passer.

Evals changed very little for a long while. The pawns did not move, Stockfish blocked the black passer and it did not push its queen side pawns that protected its king. Komodo saw an opportunity to gain a pawn and equalize material, evals jumped as Stockfish used the the time to push pawns forward and create an advanced passer in the center.

Evals climbed rapidly, Stockfish gave a rook for a bishop and removed two black passers. The engines reduced to a RBN vs RRN position, with strong queen side pawns for Stockfish.

Komodo gave its knight to remove one of the white passers, it couldn't stop the remaining two passers without losing material and the game.
Stockfish's lead is 8 points after this game, with 7 games left it secures the win in the superfinal.

There were many early exchanges in game 94, with only RRB vs RRB remaining on move 22. Komodo was a pawn up and evals were close to 0. Stockfish won the pawn back and the engines exchanged a pair of rooks. The game was adjudicated by draw rule when the engines stopped capturing pawns. Another minimatch win for Stockfish.

Games 95-96 started with a King's Gambit variant where white sacrificed a knight for a pawn and opened the black king side. In game 95 Komodo moved its king side rook so that it couldn't castle short. Stockfish immediately went on the attack and its eval jumped over 2.5. It lined up a rook and queen on the open f file and threatened a mating attack.

Komodo exchanged pieces to stop the attack on its king. It gave the piece back and the game reached a RRN vs RRN position on move 23. Evals continued to climb fast, Stockfish went two pawns up with passers in the center and on the king side.

Komodo captured the passer in the center. The engines exchanged a pair of rooks, reaching a RN vs RN ending which was hopeless for black.

Stockfish pushed the h pawn forward and the game was adjudicated quickly.

In game 96 stockfish castled short even though that left its king exposed in the corner. Komodo did not attack directly, allowing Stockfish to develop the queen side and add protection for its king. Evals came down, Stockfish gave a rook for a bishop resulting in a R vs BN imbalance. Komodo had a central passer which got as far as the 7th row. After exchanging queens the game was adjudicated in a drawn RR vs RBN position. Komodo lost this minimatch despite the substantial book advantage. Stockfish made it look so easy in the previous game, but it managed to hold as black. The lead increases to 9 points.

There were only a few exchanges in the opening of game 97. There was a small hole on the king side which made the white king vulnerable. The engines opened two files on the queen side, Stockfish had more pieces there and its eval was more than 1.5. The first piece exchange was on move 43, Komodo sacrificed a knight for a pawn on the king side and threatened the white king. The engines started to shuffle and Stockfish's eval came down. After a few exchanges both kings were exposed. Stockfish captured pawns and created passers in the center, Komodo threatened mate and Stockfish ended the game by perpetual check. 

Komodo pushed pawns on the queen side in game 98, Stockfish pushed pawns on the king side and the center was blocked by long diagonal pawn lines. Komodo focused on the queen side, it created an advanced passer. At the same time it gave a bishop for a pawn on the king side and evals became negative. The engines exchanged most pieces, did the advanced white passer compensate for the piece?

Evals did not change for a while, the engines exchanged a pair of rooks and only RB vs RBN remained. Komodo's passer stayed on the 6th rank, Stockfish also created a passer on the queen side.

Stockfish's idea was to move its king to the queen side, where it could be more useful. It was a long journey and it took a while, the evals climbed gradually. Komodo could grab the free h pawn but that would open its king to attack. Komodo preferred to hide its king behind the black pawn.

Stockfish had enough strength on the queen side to get rid of the white passer and start pushing its own. The extra piece became a deciding factor, Komodo couldn't stop the black passer without losing material. This is the 4th minimatch in a row that Stockfish wins, it leads by 10 points.

The engines castled in opposite directions in game 99. The engines made early attempts to attack their opponents' king, but after exchanging several pieces including the queens these attacks were over. Stockfish was a pawn up, evals came down to 0 and the engines shuffled until adjudication. In game 100 Komodo sacrificed a knight for pawns and opened the black king side, exposing the black king. Evals were at 0, Komodo pushed pawns on the king side and the black king walked to the queen side. The engines reduced to a Q vs QB ending, a white passer reached the 7th rank and Stockfish ended the game in perpetual check.

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