Tuesday, December 8, 2015

Season 8 superfinal, games 91-100

Finally season 8 has come to an end. The final result of the Komodo-Stockfish match is a win for Komodo, 9-2 with 89 draws. No real surprises here, we've seen this win for Komodo coming for a long time. It even grabbed another win in the last 10 games to increase the lead. The engines and their programmers can take a well deserved break, and then start preparing for season 9 - even better hardware and better engines, fewer bugs and more exciting games.

Game 91 reached a RB vs RB endgame by move 27, with Komodo a pawn up but with doubled pawns. The evals quickly dropped to 0 and the bishops and pawns were gradually exchanged. The game ended in a 6-man tablebase draw where Komodo had a two pawn advantage, the f+h rook endgame - easy if you have access to 6-man tablebases. Game 92 was very short, a 3-fold repetition on move 26 with a lot of pieces still in play.

Game 93 started with an eval advantage of over 0.6 for Komodo and a pawn advantage as well. The evals jumped up to over 1.2 when Stockfish was tempted to take a pawn, and Komodo gave a rook for a bishop to gain a passed pawn and a strong pair of bishops. Komodo fans started to fantasize about another win but Stockfish patiently defended, blocking the center with a knight, giving back the exchange and trading rooks. Komodo remained optimistic for a while longer but in the end the kings were too exposed and the game ended with perpetual check. In game 94 Stockfish could not hold on to the initial eval advantage and by move 34 the only pieces left were the queens. It took a while for the game to be adjudicated because of all the pawn moves and captures, but the draw was inevitable.

In game 95 Komodo had a small advantage after the opening even though Stockfish was a pawn up. Black's position was very cramped and less developed than white at first, but after a while the position opened a little and it seemed Stockfish could hold out. Komodo's eval started to rise again to over 1, causing more anxiety for Stockfish fans. At one point Komodo regained the pawn and had a dangerous passed pawn, but after queens were exchanged the position stabilized at a RB vs RB ending with opposite color bishops and Komodo a pawn ahead. It took a lot more moves for both engines to see that the position was drawn. In game 96 Stockfish regained the pawn very quickly, and there were many exchanges in the opening. The game reached a BBN vs BBN position on move 23, and the evals dropped after knights were exchanged. Stockfish kept a small eval that let the game continue for a long bishop shuffle before agreeing to a draw.

Game 97 was more or less balanced with a small eval advantage for Komodo. Stockfish seemed to be defending well until move 30.

For no apparent reason Stockfish weakened its king position by moving the f pawn forward. The evals started to jump immediately and within a few moves the h file was open for attacking the king.

Stockfish position deteriorated very fast. After the queens and a few pawns were eliminated the game was stopped with another Komodo win.

Komodo is only a pawn ahead but the b pawn is unstoppable with too many black pieces stuck on the king side. Another case of Stockfish not playing well in a closed position. 9-2 Komodo, not even a miracle can change the result now. In game 98 pawn lines were formed very quickly and both engines started to shuffle pieces at move 16. From move 38 the pawns became static and the game continued until nearly the 50 move rule, when Stockfish lowered its eval enough for the game to be stopped.

In Game 99 Komodo had an eval advantage of about 0.5 with many exchanges after the opening. Stockfish sacrificed a knight for two pawns, this time as a defense and not an attacking move. Pieces were gradually exchanged and the position simplified to a RBN vs RB ending. After the bishops and all white pawns were gone the RN vs R game was theoretically drawn, it just took a while to get there.Game 100, the last game, everyone was tired and wanted to go home, including the engines. Stockfish had an eval advantage for a while, but the pawn structure became static on move 26 and then the evals reached 0. The game was adjudicated as fast as the TCEC rules allowed.

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