Friday, May 31, 2024

Season 26 superfinal games 71-80

After 80 games Stockfish leads 24-14 with 42 draws. There were five drawn game pairs, 3 with two draws and two with two white wins. Leela hasn't won a game pair in the last 11 pairs. There are only 10 game pairs left in the match, I can safely say that Stockfish will be the champion. 

Games 71-72 started with a 24-ply line in the Four Knights symmetric, Metger unpin variation. All pawns were on the board and the pieces were behind the pawn lines. In game 71 the engines pushed pawns forward and continued to play behind their pawn lines. The first pawn exchange was on move 27, evals increased very slowly. The engines opened the b file, a minor piece exchange opened the c file as well. Leela captured a pawn in the center and the game reached a QRB vs QRN position. 

Leela took some time to arrange its pieces safely, it gave the pawn back and opened a diagonal for its bishop aimed at the black king. Stockfish tried to prevent the white pieces from moving forward, eventually Leela exchanged queens on move 69 and moved its rook to the 7th rank where it captured a pawn.

Leela captured another pawn on the king side, now it had two passers. Stockfish lost more material and the game ended in a tablebase win. 

In game 72 Stockfish blocked the center, Leela pushed pawns on the king side and moved its pieces there. The engines exchanged queens and minor pieces on move 27, all pawns were still on the board. Stockfish's eval started to increase, on move 34 the first pawns were exchanged and the engines opened the a file. 

Stockfish moved a rook forward on the queen side, Leela had to keep a knight on c8 to protect its b and d pawns. The white king moved to the center and Leela captured a pawn on the king side. Stockifsh moved its second rook forward, the black king was under threat and Leela exchanged pawns to try to get more space. Stockfish exchanged pieces and reduced to a RB vs RN position on move 62. It was a pawn down but evals were high. 

Stockfish captured the two black g pawns and created a passer. Leela moved its knight to the king side and Stockfish captured another pawn on the queen side. Stockfish saw the win, the engines reduced to a rook ending, Stockfish queened and mated. There were two white wins in this game pair, Stockfish leads 23-13.

Games 73-74 started with a 21-ply line in the KID orthodox variation, played in high level human games. There was one minor piece exchange and all pawns were on the board. In game 73 Stockfish traded bishop for knight and then gave a rook for a bishop. The center was blocked and it seemed Stockfish wanted to defend behind its pawns. Leela opened the center and gave a pawn, then tried to attack on the king side. Stockfish protected its king and evals came down, the engines reduced to a R vs N position with black two pawns up. The engines shuffled and traded pawns until Leela lowered its eval for the draw rule. In game 74 Leela gave a rook for a bishop, again trying to block the board. Stockfish exchanged a pair of pawns and opened the f file, the engines exchanged bishops and the game reached a QRB vs QNN position. The engines shuffled for a long time, the white king walked to the queen side, then returned to the center. On move 93 Stockfish gave a pawn and shuffling resumed. The game was adjudicated on move 119 after Stockfish gave a rook for a knight.

Games 75-76 started with a 20-ply sideline in the Caro-Kann advance, Van der Wiel attack. All pieces were on the board, there was one exchange of a pair of pawns and both kings were in the center. In game 75 Stockfish forked two minor pieces with a pawn, Leela castled long and pinned the pawn. The black king walked to the king side, Leela captured two pawns but evals came down. Leela captured another pawn and gave a rook, Stockfish was down to its last pawn and its king hid behind the pawn. Stockfish gave the rook back and reduced to a RN vs RNN position. Leela wouldn't lower its eval after exchanging knights, the engines shuffled and the game was adjudicated 25 moves later. In game 76 the engines started to exchange pieces in long PV agreements. By move 23 the game reached a RB vs RB position, the engines continued to trade pawns. Stockfish was a pawn up but evals came down, both engines had a passer on the king side. Not a lot happened, the game was adjudicated when Leela lowered its eval even though Stockfish pushed its passer to the 6th rank. 

Games 77-78 started with a 24-ply line in the Slav, Czech, Carlsbad variation played in high level human games. All pieces were on the board and the d file was open, the black king was in the center. In game 77 Stockfish castled its king, on move 20 the engines started to exchange pieces and the game reached a QRB vs QRN position. Stockfish's eval was 0, the engines exchanged rooks and started to shuffle. After exchanging queens Leela captured a pawn and created doubled passers, but Stockfish controlled them with its knight and prevented the white king from supporting the passers. The game was adjudicated a few moves later. In game 78 the engines exchanged pieces and pawns on the king side, the f file opened and Leela kept its king in the center. Stockfish was a pawn up with a passer in the center, evals came down as the engines shuffled and exchanged a pair or rooks. On move 43 the game reached a QBN vs QBB position, white was a pawn up and its passer was still on the 2nd rank. After exchanging a pair of bishops the game was adjudicated.

Games 79-80 started with a line in the Sicilian Najdorf, Opovcensky variation, played at high level human games but not recently. In game 79 Leela pushed pawns on the king side and Stockfish pushed a pawn on the queen side. As a result Leela went up a pawn and the b and g files were open. The white king walked to the king side and the black king stayed in the center, Leela's eval increased quickly. On move 39 Leela captured a second pawn and created a passer on the king side. 

Very little seemed to change for a long time, Leela pushed its passer to the 5th rank, Stockfish pushed the a pawn. The black king walked to the queen side, starting from move 70 Stockfish's eval started to increase. Leela moved a rook forward and exchanged a pair of rooks. The engines shuffled for a while and Leela's eval jumped, on move 102 Leela captured a third pawn.

After a minor piece exchange nothing could stop the white passer, Leela had two queens and Stockfish had no counter. The game quickly ended in mate. 

In game 80 the engines repeated the first 17 plys, opening the b and g files and Stockfish with a pawn up. Both kings moved forward, evals increased as the engines exchanged pieces. On move 28 the game reached a RBN vs RBB position. 

The pawns stabilized and the engines shuffled for a while, then Stockfish captured a pawn on the queen side, created a passer and exchanged rooks. The black bishops were strong enough to cover the passer's file and Stockfish kept it behind, while its king walked to the king side. When the knight moved to help Leela gave up the h pawn and Stockfish was 3 pawns up with a passer on the king side as well.

Stockfish managed to slowly push the king side passer to the 7th rank with only the black king blocking. Then it slowly pushed the queen side passer forward and Leela gave a bishop to stop it. Stockfish queened the other passer and mated. There were two white wins in this game pair, Stockfish leads 24-14.


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