Tuesday, November 8, 2022

Season 23 superfinal games 31-40

After 40 games Stockfish leads 8-3 with 29 draws. Stockfish won a game pair and its lead increased to 5. The low exit evals continued in the last 5 game pairs and there was only one decisive game. After 40 games Leela has only one game pair win, Stockfish has 6 and it appears to be heading for another superfinal win.

Games 31-32 started in a variation of the Dutch defence. In game 31 Stockfish moved its king early without castling while Leela castled long. Evals came down as the engines played out consecutive PV agreements and exchanged pieces. The game reached a RR vs RBN position with Leela two pawns up, evals were low enough for the draw rule. Game 32 started similarly with Leela moving its king and Stockfish castling long. The games did not repeat but again the evals came down while the engines exchanged pieces, mostly in PV agreements. The game reached an opposite color bishop ending, Stockfish two pawns up with doubled passers. Stockfish wouldn't lower its eval, the engines shuffled and the game ended only on move 80. 

Games 33-34 started with a variation of the Trompowsky attack played in high level human chess, where black was a pawn up. In game 33 there was a long PV agreement from the start, after which both engines castled long and queens were exchanged. Leela captured a rook for a knight, evals remained stable and not very high as the engines exchanged pieces. The game reached a R vs B ending with Stockfish a pawn up. It took Leela a long time to lower its eval, the game ended on move 86. Game 34 repeated the reverse for a while, both engines castled long again but queens stayed on the board longer. Evals came down to 0 while the engines played without exchanges. A series of exchanges that started on move 43 reduced to an opposite color bishop ending and the game was adjudicated.

Games 35-36 started with a sideline of the French defence, Petrosian variation, after the white queen moved forward on the king side. In game 35 Stockfish kept its king uncastled and the king side rook and bishop did not develop. There were several exchanges in the center that opened files and evals came down. Stockfish opened the king side to activate its king side rook, it managed to move the DS bishop and exchanged it for a knight. The game reached a RRB vs RRN position and evals were low enough for adjudication.

In game 36 Stockfish moved its queen back, there were no restrictions on the black king side. Leela castled long and its eval was low while Stockfish's eval increased slowly. Stockfish pushed pawns on the queen side and Leela's eval increased a little. All pieces were on the board until move 24, then a series of minor piece exchanges opened the center.

Leela had several weak pawns, Stockfish didn't capture the free g pawn, it probably didn't want to open the king side to avoid attacks on its king. Leela's eval decreased for a few moves, it move its queen forward on the queen side. Stockfish captured the e pawn and Leela's eval jumped though it captured a pawn on the queen side. The engines reduced to a QRR vs QRR position. 

The black pawn structure was much worse, Stockfish captured a pawn quickly and then avoided a queen exchange. An attack on the queen side got Stockfish a second pawn and then the game reached a rook ending. 

Stockfish captured all the black pawns for the price of its queen side pawns. With 3 connected passers on the king side the win was just a matter of time. Stockfish wins the game pair, it leads 8-3.

Games 37-38 started in the KID Makagonov variation. In game 37 there were no exchanges after the start and the engines locked pawns in the center. A series of exchanges opened the king side and evals came down. The game reached a QRB vs QRB position, Leela was up a pawn and Stockfish threatened the white king through an open file. After exchanging queens the engines traded pawns until the game was adjudicated. In game 38 there were only a few exchanges after the start. Stockfish formed a line of pawns across the board with knights filling the gaps. Leela had no knights left, its two bishops were not an advantage in a closed position. The engines started to shuffle on move 23, one pawn move reset the move counter, the game ended in a 50 move draw on move 114.

Games 39-40 started in a sideline of the Modern defence, Averbakh system, with the center pawns locked. In game 39 the engines opened the a file and exchanged a pair of rooks, the other files on the queen side were locked. After exchanging queens and a pair of bishops the engines started to shuffle. Evals were stable as the white king walked to the queen side. On move 58 Stockfish opened the king side, the engines reduced to a RNN vs RNN position and evals came down. Stockfish moved the rook forward, Leela gave a knight and captured two pawns. Leela pushed a passer to the 7th rank, Stockfish was on time to force a check repetition draw. In game 40 the engines played on the king side after the start. In a series of pawn exchanges the engines opened the king side, they continued to exchange pieces at a steady pace. Evals came down, the game reached a RBN vs RBN position and a few moves later the game was adjudicated.


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