After 70 games Stockfish leads 15-5 with 50 draws. Leela won a game after 50 games without a win. It also won a game pair, its second of the match. Stockfish managed to win two game pairs and its lead increased to 10. As expected the opening bias is increasing, there were 3 decisive game pairs and one with two white wins.
Games 61-62 started in a rare sideline of the Pirc defence, Bayonet attack. In game 61 the engines played out a long PV agreement, both kings were exposed and moved without castling to the king side. Queens were exchanged and Leela was a pawn up with a central passer. The game reached a RBN vs RBN position and evals slowly came down. The engines mostly shuffled for a long time, Stockfish captured the passer on the 7th rank and the game was adjudicated on move 72.
In game 62 the engines entered a different PV agreement, this time the h file was opened and both engines castled long. Evals were stable for a while, Stockfish thought Leela's move 26 was a mistake and its eval jumped. Leela thought for 11 minutes and its eval also jumped, it was very difficult to see what the engines understood. It was evident that Leela moved a knight and moved it back, losing 2 tempi. Also, Leela had a knight on h5 that was weak, almost trapped. Evals slowly increased though the engines seemed to be shuffling.
Evals continued to increase, Leela played waiting moves while Stockfish slowly moved its pieces to the queen side. When it was ready Stockfish pushed pawns on the queen side and opened the a file. Now the black king was in danger and Leela was effectively playing a piece down.
Leela gave a rook for the bishop and freed its knight, but it was too late. Stockfish exchanged queens, captured two pawns and pushed a passer to the 7th rank. Leela lost material and was mated. Stockfish wins the game pair, it leads 13-3.
Games 63-64 started with a rare sideline of the French defence, Paulsen variation. In game 63 the engines castled in opposite directions. Evals started to increase on move 15, both queens moved forward and captured a pawn defender of the opposing king, then queens were exchanged. Stockfish pushed pawns on the king side and the game reached a RRB vs RRB position.
Stockfish opened the king side and the white king walked to the center. Leela gave a pawn and opened the queen side, it pushed a passer and Stockfish gave a bishop to capture it. After exchanging a pair of bishops Stockfish was two pawns up with two passers while Leela was down to 2 pawns.
Leela captured the f pawn while Stockfish pushed its passers. Leela captured a passer and was on time to protect its pawns with the king and prevent Stockfish from queening the second passer. Leela captured the remaining black pawns, the game ended in a tablebase win.
In game 64 the engines castled in opposite directions again. Stockfish gave a pawn on the queen side and half opened the a file for its rook. There were a few minor piece exchanges, Stockfish had strong pawns in the center and evals slowly increased. Leela gave a pawn on the king side to develop its rook, then it created a passer on the queen side, giving Stockfish a central passer at the same time. The black king had weak pawn support and evals jumped. In a series of exchanges the engines reduced to a RRB vs RRB position.
After a few pawn trades only one black pawn remained on the queen side and the black king was an easy target for the white rooks. Both engines had passers on the g file, both were blocked one square before promoting. Leela had to use a rook as a blocking piece, effectively Stockfish had a piece advantage and it was able to capture the black passer on g2.
Stockfish captured the black f pawn, then slowly pushed its d pawn forward. Leela delayed with checks but ultimately had to give its bishop to stop the queening. After that Leela gave up and was mated. There were two white wins in this game pair, Stockfish leads 14-4.
Games 65-66 started with a 14-ply book in the KID semi Averbakh system. In game 65 Leela pushed pawns on the king side and kept its king uncastled. Leela's eval increased after move 14 and it surprised Stockfish on move 15. Stockfish thought for 21 minutes, it captured a pawn on the queen side and its eval jumped over 2. Leela pushed a pawn to h6 and trapped a black bishop in the corner. On move 20 Leela regained the pawn on the queen side, Stockfish thought this was a mistake and its eval dropped back. There was a series of exchanges that opened the position, Leela captured a knight and had a passer on the 7th rank, but Stockfish threatened the white king. Stockfish captured the passer and a knight, Leela was a pawn up but evals were close to 0. There were too many pieces for the draw rule, the game was adjudicated after the engines exchanged a pair of rooks.
In game 66 again Stockfish pushed pawns on the king side and didn't castle its king. The engines opened a file on the queen side, Stockfish walked its king to the king side corner. On move 19 Leela chose to exchanged a pair of bishops, Stockfish thought this was a mistake, evals started to increase. Stockfish concentrated forces on the king side and the black king walked back to the center. When it was ready Stockfish opened the h file.
The engines exchanged a pair of rooks, Leela defended the back rank against the white pieces. Stockfish managed to capture a pawn, the black king ran to the queen side for safety. Stockfish reduced to a QRN vs QRN position and captured two more pawns.
Stockfish had 2 passers, after exchanging queens and trading a pair of pawns Stocfish added another passer. Leela captured one passer, lost its knight for the second one but the third promoted to a queen and Stockfish mated. Stockfish wins the game pair, it leads 15-4.
Games 67-68 started in the Trompovsky attack, Raptor variation. In game 67 Stockfish grabbed an early pawn with its queen, Leela pushed a pawn to h6 and both kings stayed in the center uncastled. The engines opened the board with a few exchanges and then queens were off.
Evals increased though it seemed the engines were shuffling, Stockfish had many weak pawns to protect and Leela moved its pieces trying to decide where to attack. After a while Leela captured two pawns and exchanged a pair of rooks. Stockfish captured a pawn back, equalizing material but evals were high.
Stockfish's defence gradually collapsed, Leela captured the g pawn and then the h pawn, creating and advanced passer. Stockfish had to give a bishop to stop the promotion. Leela slowly improved using its piece advantage. Stockfish couldn't prevent a queening followed by mate.
In game 68 there were no exchanges after the start, the engines locked pawns in the center and king side to form a long pawn wall. On move 34 a pawn exchange opened the b file, after a bishop exchange the engines started to shuffle. Stockfish wouldn't lower its eval, it extended the game with piece exchanges and by move 152 only BN vs BN remained. After Stockfish's eval was low enough there were still too many pawns for the draw rule, the game finally ended on move 256 by a 3-fold repetition. Leela wins the game pair, Stockfish leads 15-5
Games 69-70 started with a sideline of the French, Winawer, retreat variation, with the center locked and black a pawn up. In game 69 Leela used a rook to regain the pawn and sent its queen forward on the king side. Stockfish didn't castle its king, its king side rook moved and the queen side was open. Leela castled late and evals came down, the engines traded a pair of rooks and started to shuffle in a QRN vs QRN position. There were too many pawns, the engines reduced to a queen ending and the game was adjudicated on move 93. In game 70 Stockfish used its queen to regain the pawn, Leela moved its king without castling and Stockfish also kept its king uncastled. The engines opened the king side a little but did not try to attack, instead they shuffled for almost 50 moves. A few exchanges opened the queen side, evals came down and shuffling resumed. On move 113 the engines started to exchange pieces, and the game was adjudicated on move 131.
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