Friday, November 27, 2015

Season 8 superfinal, games 61-70

After 70 games in the Komodo-Stockfish superfinal match, Komodo is leading 4-1 with 65 draws. The last 10 games have all been draws, again. An important change is that from game 67 the openings are supposed to be more unbalanced, as preselected by Cato to try to lower the draw rate. The evals out of the openings are higher than before, but the first 4 games 67-70 were still draws. Still 30 games to go so we will have to wait and see.

Game 61 was very short. Stockfish went for the b pawn with the queen, and Komodo almost trapped it, leading to a draw by repetition. Game 62 started with many captures, reaching an RN vs RN ending in move 28 with Stockfish a pawn up. Both engines continued with 0 evals and eventually the game was adjudicated even though both had dangerous passed pawns. There was a possible repetition in the end but it wasn't played out... a draw in any case.

In game 63 Komodo started with a small eval advantage, but it disappeared when almost all the queen side pawns were captured and the pieces left were QRN vs QRB. Then Komodo's eval went up again as it got into the black back rank, but once the queens were exchanged Stockfish secured a king side fortress. It took many shuffling moves for Komodo to realize there was nothing to do, finally it broke the pawn structure to get out of the 50 move draw. This only led to a repetition draw later. In game 64 Stockfish held on to an eval advantage with an advancing passed pawn. All pieces focused on attacking and defending this pawn until the position was stuck, the engines chose to end with a repetition of checks.

Game 65 reached a RB vs RB ending by move 22, and then continued for more than 100 shuffling moves with a few pawn moves to reset the 50 move rule. Komodo insisted it had a small advantage, and the game could not be adjudicated until it realized what everyone knew for so long - it was a draw... Game 66 was played in a different line but just as drawish. This time the game reached a B vs N at move 30 and both engines had a 0 eval, allowing the game to stop without a long wait.

Game 67 was the first of the 'Cato openings' of the superfinal. There was a lot of hope that the games would be more decisive the way these openings were chosen. The first 4 were draws but there were higher evals in these games, so there is still hope.

Komodo started with an eval advantage that got up to 0.63 in game 67. Stockfish defended well and after 26 moves the pieces left were QRB vs QRB, Komodo a pawn up, passed and isolated. After the queens were exchanged and the pawns were taken one by one the evals dropped to zero. The game reached a 6-man drawn position. In game 68 Stockfish held its advantage longer and gave an eval of 0.9 for the isolated passed pawn it had, also a pawn up. Komodo defended well and Stockfish couldn't convert a win, gradually the pieces were captured until there was a rook ending. Stockfish was still a pawn up but not enough for a win.

In game 69 Komodo again had an eval advantage that got up to 0.7. Material remained equal but Komodo created a passed pawn after the queens were exchanged. Pieces kept being captured until there were only B vs N. It then took a while for both engines to lower their evals to agree on a draw. Stockfish didn't get as much out of the opening in game 70. As the game progressed Komodo was attacking on the king side and Stockfish countering on the queen side. Both engines started to see perpetual check in the future but Stockfish went for a bishop and pawns for rook exchange, forcing the draw when Komodo was left with KR with no pawns.

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