Season 22 superfinal games 71-80

After 80 games Stockfish leads 25-8 with 47 draws. Stockfish won two more game pairs, with 20 games and a +17 lead it is very close to win the match formally. Of course there is no doubt it is going to win. KomodoDragon won another game and lost the reverse, the 8th time in this match. Curious that there has been one game pair with two white wins in each report I wrote so far this match, two more to go.

In game 71 KomodoDragon castled long and Stockfish kept its king uncastled in the center. The engines played out a long PV, KomdoDragon went a pawn up and opened a file in the center. The game reached a QBN vs QBN position, evals were around 1.5. However, evals dropped after the bishops were exchanged, Stockfish moved its pieces forward and threatened the white king. The white knight helped defend the king and KomodoDragon gave checks with its queen until the game was adjudicated. 

In game 72 again Stockfish castled long and KomodoDragon kept its king uncastled in the center. This time Stockfish pushed pawns on the king side and didn't open the center. There was a long PV agreement in which the engines opened the queen side and exchanged many pieces. The game reached a RBN vs RBN position on move 24, with white a pawn up and a passer on the queen side.

The engines exchanged pawns and opened the position, the black rook developed through the h file. KomodoDragon's main concern was the white passer, it decided to give its knight to capture the passer and another pawn. This left Stockfish with one last pawn, all the pieces on the board moved either to attack this pawn or defend it.

This 9-man position was easy enough for this level of engine play, not sure how easy it is for humans. KomodoDragon couldn't afford to lose a piece for the last white pawn. Stockfish captured the black pawn quickly, it took a while but eventually Stockfish managed to capture a piece anyway using a discovered check. The game ended in a tablebase win after that. Stockfish wins the game pair, it leads 23-7.

In game 73 there were a few minor piece exchanges and one pawn exchange after the start. Evals came down and the engines started to shuffle on move 32. KomodoDragon's eval was too high for the draw rule, On move 74 KomodoDragon's eval dropped to 0 and then the exchanges started. The game was adjudicated 30 moves late in a RR vs RN position. In game 74 there were many early exchanges, only RBN vs RBN remained on move 20. Evals came down gradually, the engines exchanged pawns and bishops and the game was adjudicated by move 47.

Games 75-76 started with an 18-ply book in the French Winawer, Petrosian variation. The center was blocked and in both games black castled long. In game 75 Stockfish moved a knight forward on the queen side. KomodoDragon gave a pawn and created a passer on the queen side, after castling long it traded a rook for the black forward knight. The exchanges continued until only BBN vs RBN remained, KomodoDragon was a pawn up with two passers. Evals were 0 and the game was adjudicated by the draw rule. 

In game 76 KomodoDragon pushed pawns on the king side, Stockfish didn't think this was a good plan and its eval increased. KomodoDragon opened the g file, there seemed to be no safe direction for the white king to castle. However Stockfish wasn't worried, and at the end of a PV agreement on move 24 KomodoDragon's eval jumped, it acknowledged it had a problem.

Stockfish pushed the h pawn, the white king was safe in the center. After exchanging a pair of rooks the white king walked to the h file and moved its queen side rook to the open g file. KomodoDragon kept its pieces on the queen side to protect its king from the coming invasion, Stockfish captured the h pawn and created a passer. 

KomodoDragon tried to counter on the queen side and created a passer there, but it lost a rook for the white h pawn. The game continued for 25 more moves but with a rook advantage the outcome was obvious. Stockfish wins the game pair, it leads 24-7.

In game 77 the evals were relatively low after book, the engines locked the center and exchanged a few minor pieces. KomodoDragon castled long and Stockfish pushed pawns on the queen side. The engines opened a file on the king side and then reduced to a bishop ending with low evals. KomodoDragon created a passer and wouldn't lower its eval for the draw rule. The game was adjudicated after 25 shuffling moves. In game 78 Stockfish also castled long, this time it pushed pawns on the king side. The engines played out a long PV agreement, KomodoDragon went up a pawn and it had two passers in the center still close to their initial square. Stockfish placed a knight on e6 and blocked the passers, both kings were vulnerable. KomodoDragon threatened mate on the queen side, then gave a knight for a pawn on the king side. Stockish gave the material back and attacked the black king, however evals were low and the game was soon adjudicated.

Games 79-80 started with a 16-ply book in the Sicilian Dragon, Yugoslav attack variation, still in theory of high level human chess. The games then repeated 26 more plys where the engines castled in opposite directions, black gave a pawn and opened the queen side, white captured a rook for a bishop and black regained the pawn. All the black pawns were on the king side, white had two passers on the queen side. 

In game 79  KomodoDragon exchanged bishop for knight, Stockfish's eval came down for a while but it then came back up. KomodoDragon pushed the a pawn forward, eventually Stockfish gave a knight to get rid of it. KomodoDragon was then up a rook for pawns, the engines traded a pair of rooks and reached a QRN vs QB position.

Stockfish was 3 pawns up and the white king was exposed, however that was not enough to compensate for a rook. The engines traded pawns until there were no white pawns left, the white king started to move forward protected by pieces. Stockfish exchanged queens and the game soon ended in a tablebase win. 

Stockfish had a different approach in game 80, it kept the queen side pawns as they are and traded both its pawns on the king side. Then it exchanged pieces and gave back the material so that it was only a pawn up in a QRB vs QRB position. 

Both engines were sure Stockfish was going to win, though the material advantage was small and indeed the black pawns had a head start. KomodoDragon made no effort to push its pawns, it was busy avoiding an exchange of pieces. Perhaps the black king was vulnerable without pawn support. After a while the engines exchanged queens, and Stockfish pushed its pawns. KomodoDragon blocked the white pawns but eventually lost the rook and the game. There were two white wins in this game pair, Stockfish leads 25-8.