After 80 games Stockfish leads 23-17 with 40 draws. Leela won a game pair and reduced Stockfish's lead to 6 wins. The other game pairs were draws, with 3 having two white wins. Stockfish hasn't won a game pair for 8 straight pairs played, while losing 2. There is still hope for Leela, though it may be too late since there are only 10 game pairs left in the match.
Games 71-72 started with a rare sideline in the Nimzo-Dutch, Alekhine variation. In game 71 there were a few minor piece exchanges and the engines opened the d file. Stockfish gave a pawn, the engines exchanged a pair of rooks and evals were mostly stable. On move 28 the engines opened the a file.
Evals started to increase though the engines seemed to be shuffling. Leela gave two pawns on the queen side and captured a rook for a bishop. Leela then captured the two black pawns on the queen side, it was a pawn up in a QRB vs QBN position and evals were high.
Stockfish tried to avoid exchanges, Leela pushed the h pawn and it became a passer. Stockfish lost a bishop and captured the passer, it saw mate in its PV. Leela took a longer route, in the end a series of exchanges resulted in a tablebase win.
In game 72 more pieces stayed on the board, a pawn exchange opened the a file and evals came down. After some shuffling the engines opened the queen side and Stockfish went a pawn up. Stockfish traded its queen for a rook and a bishop, the engines reduced to a RBN vs QN position with white a pawn up. After 20 moves the engines traded minor pieces, when evals were low enough the game was adjudicated. Leela wins the game pair, Stockfish leads 20-14.
Games 73-74 started with a rare sideline in the Old Indian defense, normal variation. In game 73 the engines locked the center and there were no exchanges after the start. Leela offered a bishop and Stockfish refused to weaken its king. The engines opened the c file and exchanged a pair of knights, Leela captured the g7 pawn, then Stockfish captured two pawns on the king side. The black king looked vulerable, Stockfish exchanged queens and evals started to increase. The game reached a RRB vs RRB position on move 40.
After a pawn exchange on the queen side all the black pawns were isolated. Leela protected its d5 pawn with the bishop and started capturing black pawns. Stockfish held on to its a pawn, Leela pushed passers and moved its king forward. Stockfish lost material trying to stop the passers, the game ended in a tablebase win.
In game 74 there was one pair of pawns exchanged after the start, all files remained closed. The engines mostly shuffled behind their pawn lines but evals slowly increased. A pawn exchange on move 32 created passers in the center for both engines, on move 35 the first minor pieces were exchanged. Stockfish captured the doubled black passers in the center by move 42.
Leela had some initiative, its rooks controlled open files in the center. Leela attacked the exposed white king with a rook and queen, it also captured pawns on the queen side. Stockfish sent a rook and queen to attack the black king, it gave a rook for a bishop but then Leela had to give a rook to avoid mate. Both engines pushed passers forward, Stockfish queened first and mated. There were two white wins in this game pair, Stockfish leads 21-15.
Games 75-76 started with a 24-ply sideline in the Sicilian accelerated Dragon, Modern variation. White pushed pawns on the king side and its king was uncastled in the center, black had an eval advantage. In game 75 the engines played out a long PV agreement, pawn exchanges opened the center and king side, most pieces were exchanged and the game reached a RBN vs RBN position. Stockfish had a passer in the center, evals came down as Leela blocked the passer and kept its pieces safe. Leela gave a rook for a bishop, all pawns were captured and the game was adjudicated. Game 76 repeated game 75 for 39 plys, reaching the same RBN vs RBN position. Stockfish kept its pawns safe and blocked the black passer. The engines reduced to a rook ending, evals came down and the game was adjudicated.
Games 77-78 started with a 22-ply line in the Ruy Lopez, Arkhangelsk variation, played in high level human chess. All pieces and pawns were on the board and the black king was in the center uncastled. In game 77 Stockfish castled long and tried to attack the king side but was not strong enough. Leela's eval started to increase, it opened a file in the center and exchanged minor pieces. In a long PV agreement Stockfish's eval came down and then jumped up, Stockfish created a passer in the center while Leela captured a pawn and created an advanced passer on the king side. After another pawn trade Leela cleared all the black pawns on the king side and added 2 more connected passers.
In another long PV agreement each engine blocked an advancing passer and eventually captured it. The minor pieces were traded, on move 50 the queens were exchanged and the game reached a double rook ending with white a pawn up and two passers on the king side.
Leela pushed the passers slowly forward, Stockfish captured one while Leela captured a pawn on the queen side. Stockfish blocked the passer on the 6th rank and Leela captured another pawn and created a passer on the queen side. Leela pushed both passers to the 7th rank, Stockfish couldn't stop a queening and the game ended in a tablebase win.
In game 78 Leela was more active in its king side attack, it moved its queen to h3 and forced Stockfish to weaken the pawn support for its king. Stockfish ignored the attack, it opened the a file and moved its queen to the queen side. Leela gave a pawn, chose not to take the knight Stockfish offered and added a second rook to the attack.
Stockfish moved the queen to the king side, Leela captured the h pawn but that was the end of its attack. Leela's queen side seemed solid, yet evals continued to increase. Stockfish exchanged queens and a pair of bishops, then after a while it traded a rook for a knight and captured a pawn. The game reached a RNN vs RRB position.
Leela had a material advantage, but the white knights were very strong together and covered many squares. Stockfish exchanged pawns and created a passer in the center. Leela captured two pawns but lost the bishop, it gave a rook for a knight but couldn't stop the white passer queening, mate followed a few moves later. There were two white wins in this game pair, Stockfish leads 22-16.
Games 79-80 started with a rare sideline in the Queen's Indian defense, Kasparov-Petrosian variation. In game 79 the engines opened files with pawn exchanges in the center and queen side. Leela went a pawn up and exchanged queens, then it captured another pawn. In a series of exchanges Leela traded a rook for two minor pieces and the game reached a RB vs BBN position on move 30.
Leela pushed its two passers forward, Stockfish captured one but lost a bishop. Stockfish blocked the other passer with the knight, Leela had a very hard time trying to improve its position. On move 56 Leela captured a pawn, on move 73 it gave a pawn and then the black knight moved. Leela captured a pawn, only on move 88 it managed to push its passer forward. Stockfish saw a quicker win, but eventually it started to lose material and the game ended in a tablebase win on move 105.
In game 80 Stockfish pushed the h pawn forward and it was exchanged on h6, Leela castled short despite this and Stockfish kept its king in the center. Leela pushed pawns and opened the queen side, the engines exchanged minor pieces in the center. Stockfish's eval started to increase while Leela's eval was stable and even decreased a little.
The engines seemed to shuffle for a while, though Stockfish's eval steadily increased. After move 38 Leela's eval reacted as well. Stockfish blocked the center with its major pieces, on move 51 it exchanged a pair of rooks and reduced to a QRB vs QRB position.
Stockfish exchanged its b pawn and moved its queen to the back rank. It captured the black d pawn and exchanged bishops, seeing the win far in its PV. After exchanging queens the white king moved forward on the king side. Stockfish was only one pawn up, but after exchanging a pair of pawns it had a pawn majority in the center. Leela had a passer but the white king blocked it long enough until it captured the black e pawn. The white passers were faster and the black king was trapped, the game ended in a tablebase win before mate. There were two white wins in this game pair, Stockfish leads 23-17.
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