Season 24 superfinal games 81-90

After 90 games Stockfish leads 17-13 with 60 draws. Stockfish increased the lead to 5 wins, and then Leela won a game pair and reduced the lead back to 4 wins. The Leela game pair win came after 24 game pairs with 6 game pair wins for Stockfish and none for Leela. There are only 5 game pairs left to play, it is safe to assume Stockfish will win the match, but Leela may yet reduce the gap .

Games 81-82 started with a rare sideline of the KID Saemisch, Yates defense. In game 81 there were a few pawn exchanges after the start, the engines opened the a file and evals came down. The engines exchanged a pair of rooks, then Leela moved a rook to the 7th rank and the engines cleared the b file pawns as well. The exchanges gradually continued, evals were low and the game was adjudicated in a RB vs RN position. In game 82 the engines played a slightly different line, they delayed exchanging pawns a little but again the a file was opened. Leela moved a rook forward but Stockfish didn't try to exchange rooks. Nevertheless evals came down while the engines exchanged minor pieces. Stockfish pushed pawns on the king side, Leela gave a pawn and both engines created a passer in the center. After exchanging queens evals were close to 0, Leela gave a rook for a bishop and captured all but one white pawn. The game was adjudicated in a RR vs RB position.

Games 83-84 started with a rare sideline of the Dutch, Hopton attack. In game 83 a pawn exchange opened the center, Leela castled long, and queens were off early. Evals stayed stable around 1, Stockfish castled long and Leela went a pawn up with a passer on the king side. On move 29 the game reached a RBN vs RBN position, the kings moved to the center. Both engines pushed pawns on the     queen side, Leela captured another pawn and had doubled pawns on the queen side. Stockfish's eval started to fluctuate, on move 49 the engines exchanged bishops and evals started to increase.

All the white pawns were isolated, Leela had to be careful and patient. Stockfish captured the d pawn and created a passer. Stockfish pushed its pawns forward and they became targets. Leela protected its h pawn, but managed to capture all the black pawns, keeping two white pawns. 

Progress was still slow, Leela pushed both pawns until they were on the 6th rank. Stockfish blocked one pawn but eventually lost its knight for the second, the game ended in a tablebase win.

In game 84 the engines followed the reverse game for 25 plies, with Stockfish castling long and the queens off. Leela castled long, the engines seemed to be shuffling but Stockfish's eval slowly increased. After move 29 Leela's eval increased as well, in a series of exchanges the engines reduced to a RBB vs RNN position with white a pawn up and doubled passers on the king side. There were a few pawn exchanges, Leela regained the pawn, Stockfish created a passer on the queen side and Leela had doubled passers in the center. 

Stockfish pushed the g pawn so it was protected by its rook, then turned to attack the doubled black pawns. Leela tried to protect both pawns with a knight, Stockfish traded bishop for knight and captured both pawns. Leela couldn't block both the white passers, Stockfish pushed the c pawn forward, queened and mated. There were two white wins in this game pair, Stockfish leads 16-12.

Games 85-86 started with a rare sideline of the Sicilian main line, with 5.. Qc7 (instead of the Najdorf 5.. a6). In game 85 after a few development moves there was a series of exchanges including the queens. Evals came down, Leela castled long and Stockfish kept its king uncastled. The game reached a RRN vs RRN position, not a lot happened until the engines reduced to a rook ending and the game was adjudicated.

In game 86 most pieces stayed on the board after the start. There was a hole in the pawn support on the king side and Leela chose to castle long. Stockfish chose to abandon its queen side pawns and castled short. Leela captured a pawn with its queen, evals started to increase. The white pieces were mostly on the king side, but the main issue was the safety of the black king on the other side. The white knights dominated the center, Stockfish moved its rooks to the half open b file, the black queen was stuck in a defensive role in front of the pawns. By move 34 Stockfish was ready for attack.

In a long PV agreement Stockfish sacrificed a knight and opened the a file, then it gave a rook for a knight and a bishop. Leela used a rook to hide its king, its eval drifted down while Stockfish's eval increased. In a series of exchanges the engines reduced to a Q vs RR ending with white two pawns up. 

Stockfish gave the c pawn and pushed the f pawn forward to the 7th rank. Leela finally realized its was losing, it couldn't take the f pawn because it would lose a rook in a check fork. Stockfish created a second passer and pushed it forward supported by the king. Leela wouldn't give material to stop the queening, the game quickly ended with two white queens. Stockfish wins the game pair, it leads 17-12.

Games 87-88 started with a rare sideline of the Hungarian (Benko) symmetrical variation. In game 87 Leela's eval increased from the start, it pushed the h pawn forward until it reached h6. In a very long PV agreement the engines opened the king side, they exchanged minor pieces and queens, Leela's eval drifted back. Leela pushed pawns on the king side, Stockfish captured a pawn on the queen side but evals slowly increased again. Leela focused on the king side, it placed a knight on e6 and Stockfish felt the pressure.

Leela exchanged a pair of pawns, creating a pawn majority on the king side, then it placed its knight on f6. Stockfish had no counter, when it was ready Leela attacked the black king and captured the h7 pawn. The engines reduced to a double rook ending, Leela with advanced connected passers on the king side. The black king had to run to get out of the way. 

Stockfish delayed with checks, but eventually Leela queened the h pawn. Stockfish lost material fast, Leela queened the g pawn as well and mated.

In game 88 Stockfish again pushed the h pawn, but after two long thinks and a 2-fold repetition it decided to exchange it and to open the h file. Stockfish's eval dropped and a few moves later so did Leela's eval. Stockfish walked with its king to the king side, the engines shuffled and exchanged a pair of knights, Stockfish couldn't find a way to attack the black king. For a few moves Leela's eval jumped over 1, it wasn't happy with its PV. Then after thinking for 8 minutes Leela changed its move to Stockfish's PV and its eval dropped back down. In a long PV agreement the engines reduced to a QR vs QBB, Stockfish gave checks and the engines traded pawns. Evals were close to 0, after Stockfish gave a rook for a bishop the game was adjudicated. Leela wins the game pair, Stockfish leads 17-13.

Games 89-90 started with a 20-ply rare sideline of the Ruy Lopez, Chigorin defense, with all pieces and pawns still on the board. In game 89 evals came down from the start, the engines exchanged most pawns on the queen side and a few minor pieces. Stockfish had a passer on the queen side, it managed to get as far as the 3rd rank in a QRB vs QRB position. The engines started to shuffle with evals close to 0, the game ended in a 3-fold repetition. In game 90 the engines locked pawns on the queen side at first, then in a long PV agreement cleared most of the pawns on the queen side. Evals came slowly down, the first piece was exchanged on move 26, in another long PV agreement the engines reduced to a Q vs RB position. Stockfish was reluctant to lower its eval, the game was adjudicated after 30 more moves.