After 50 games Stockfish leads 7-4 with 39 draws. Stockfish extended its lead to 3 after two game pair wins and only one game pair win for Leela. The gap can still be closed by Leela, this is only the halfway point of the superfinal. It appears though that Stockfish has better chances of winning.
In game 41 both engines castled long, there were many early exchanges and long PV agreements. On move 23 only QRN vs QRB remained with low evals. The game reached a N vs B ending, Leela was a pawn up but it was only good for a draw.
In game 42 Stockfish castled long and Leela chose to keep its king uncastled. Stockfish pushed pawns on the king side, then exchanged queens and went a pawn up. Stockfish's eval remained around 1, after some shuffling it moved its rooks to the king side. Leela finally castled short on move 31, it stopped to think for 19 minutes when Stockfish exchanged pawns and opened the king side. Leela's eval jumped a little but was still under 1.
Stockfish's eval increased a little, Leela traded pawns on the queen side, perhaps to create counter threats on the white king. On move 40 Leela moved without thinking as it often does, Stockfish thought this was a blunder and its eval jumped close to 4. It pushed the g pawn, Leela realized it couldn't take the pawn and its eval jumped over 2. Stockfish now had a passer facing the black king, with a back rank mate threat. Leela quickly exchanged pieces and reduced to a R vs BB ending.
Leela captured the g pawn, Stockfish did not blunder the 7-man ending though there were several moves with only one winning choice. It managed to push the b pawn forward, finally promoting to a queen on move 69. The game ended shortly afterwards. Stockfish wins the game pair, it leads 6-3.
In game 43 the engines castled in opposite directions, the white king had little pawn support while the black king was weak on dark squares. After exchanging the DS bishops Leela pushed a pawn to h6. Stockfish became more uncomfortable and its eval went over 1.5, Leela's eval was around 1 when the game reached a QRN vs QRB position on move 36.
The engines played out long PV agreements, Stockfish's eval kept increasing. Stockfish captured the white h pawn while Leela captured the black a pawn and created a passer on the queen side. Stockfish tried to use its pawn majority on the king side without success, Leela's confidence grew and its eval increased. On move 55 the engines exchanged queens and evals were over 4.
Leela pushed pawns on the queen side and the white king came forward to support. Stockfish gave a pawn to clear a path for the f pawn, Leela used its knight to block the black pawns. After exchanging rooks Stockfish could not stop the advancing white pawns, Leela queened a pawn and the game ended in a tablebase win.
In game 44 Stockfish castled short and the DS bishops stayed on the board longer. Eventually Leela also castled short, Stockfish created a passer on the queen side, its eval stayed around 1. On move 31 the game reached a QRR vs QRR position and Stockfish went a pawn up. It couldn't push the passer forward and the engines mostly shuffled while evals came down. On move 59 Leela regained the pawns and exchanged queens. Stockfish went a pawn up again but the double rook ending was a draw and the game was adjudicated. Leela wins the game pair, Stockfish leads 6-4.
Games 45-46 started with a 24-ply book in the English symmetrical, hedgehog variation. There was only one pawn exchange and all pieces were on the board. In game 45 the engines opened the queen side, then exchanged minor pieces and a pair of rooks. Leela had a doubled passer on the queen side but it couldn't push it forward. The engines shuffled and evals came down, the game was adjudicated when the pawns stopped moving on move 74.
In game 46 there were no exchanges and the queen side stayed closed. On move 25 the pawns stopped moving and the engines started to shuffle. On move 66 Stockfish exchanged knights and then continued the shuffle. Evals increased a little, Stockfish's eval was over 2 when on move 95 it finally pushed a pawn on the king side. The king side opened and most of the black pieces were too far to help the black king. Evals increased quickly as the black king ran from the attacking white pieces.
Leela tried to block the center to protect its king. Stockfish sacrificed a rook and its queen broke through the center, for a few moves Leela's eval dropped. It was false hope, the black king was in a net and Leela had to give material to avoid mate. The game reached a QB vs RBB position on move 120.
There were too many targets for Stockfish as well as an exposed black king. Stockfish captured two pawns, then captured a bishop. The white passers moved forward and mate followed. Stockfish wins the game pair, it leads 7-4.
In game 47 the center was blocked, Leela pushed the h pawn and exchanged it, letting the rook out. Both engines castled long and the queens were exchanged. Evals came down as the white king walked to the king side and Leela opened the queen side. A series of exchanges reduced to a RB vs RN position and Leela went a pawn up. Leela had a passer in the center but Stockfish kept the white king away, evals were low enough for adjudication. In game 48 the king side remained closed, Leela moved its king there without castling. After a few minor piece exchanges Stockfish castled long, then the engines started to shuffle. Stockfish's eval stayed around 1, one pawn exchange and a few pawn moves kept the shuffle going until move 121. Evals came down after the engines opened the king side and started exchanging pieces. The game reached a RN vs RN position and was adjudicated on move 142.
Both engines thought the book opening of games 49-50 was a draw with evals close to 0. The games repeated the first 12 plys, opening the center with white a pawn up. In game 49 Stockfish castled long and gave a second pawn, Leela was behind in developing the king side. By the time Leela's king side pieces moved and it castled its king Stockfish regained the two pawns and queens were off. Evals were around 0 and the engines continued to exchange pieces, the game reached a tablebase draw on move 51. In game 50 both engines kept their kings in the center without castling. Stockfish was a pawn up but evals stayed around 0. The engines gradually exchanged pieces until only RB vs RB remained on move 38, the game reached a tablebase draw again.
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