Wednesday, October 24, 2018

Season 13 superfinal, games 1-8

The TCEC cup is over, Stockfish won the event after beating Houdini in the final. Perhaps more interesting was the semi-final match against Leela (Lc0). Leela beat Ethereal and Fire in the earlier rounds in very long matches. Leela seemed to play the openings and middlegames better, but it would sometimes blunder in the endgames or be surprised by a perpetual check draw by the opponent. Leela was no match to Stockfish in season 13, it will be very interesting to see it in the next season. It will surely reach the premier division, I'm not sure whether it can handle the top 3.

The Stockfish - Komodo superfinal of season 13 has started. After 8 games Stockfish leads 2-0 with 6 draws.

Komodo opened the queen side early in game 1, and after a series of exchanges only RBN vs RNN remained on move 26. Stockfish had a queen side passer which looked dangerous, with an eval over 1.

Evals remained mostly unchaged for a while. The engines exchanged a pair of knights and Komodo used its extra pawn on the king side to create a passer in the center. Stockfish's eval started to increase after it won a pawn. It then abandoned its queen side passer and sent its rook to the king side and created passers there.

Stockfish finished the game with a rook for knight sacrifice.

The black pawn on f4 could not be saved and the 3 white passers that remained were eventually unstoppable.

In the reverse game Komodo had a pawn majority on the queen side but no passer. The pieces remained on the board longer, and evals started to drop to 0 after the engines exchanged all the rooks. The game reached a BN vs BN position on move 61. The engines continued to shuffle and exchange pieces until adjudication with only pawns left. First minimatch goes to Stockfish.

In game 3 Komodo's king remained uncastled, yet it was not in danger after the engines exchanged most pieces early. Stockfish's eval started around 1 but started to come down after 25 moves. The game ended in a repetition with RBN vs RBN on the board. Game 4 also had many early exchanges, resulting in a RBN vs RBN position. This time Komodo was a pawn up and had a 3 vs 1 pawn majority on the queen side. Komodo's eval was over 1.5 while Stockfish reduced to an opposite color bishop ending. Komodo had a queen side passer but it could not push it beyond the 6th rank. Stockfish was able to hold the white king back. It took Komodo a very long time to agree to a draw after 175 moves.

Stockfish castled long in game 5, and then it pushed the queen side pawns to force back a black bishop. This left the white king very exposed, and Komodo gave a knight while its pieces controlled the center where they could threaten the white king. Komodo thought it had enough compensation for the piece, Stockfish's eval was over 1 but it had to be careful.

The white pieces were static and pinned down, but somehow the white king remained safe. Komodo captured two pawns on the king side and created a passer in the center. Stockfish exchanged a few pieces, its king was still exposed but out of danger since only Komodo's queen could attack. 

The white pieces became more active, after making sure the black passer was blocked Stockfish started to plan its attack. Komodo's king side was vulnerable and Komodo had to defend while being a piece down. Stockfish's eval was winning as it left a pawn hanging for Komodo to take.

Stockfish sacrificed a knight for the g6 pawn and pinned the rook after it took the knight. All the black pieces surrounded the king, leaving the c7 pawn unprotected. Stockfish's c pawn became an advanced passer and this was enough for a win.

In the reverse game 6 both engines castled short and the position remained closed with all pawns on the board. Komodo had a space advantage with evals over 1. Stockfish exchanged its bishops for white knights and after queens were exchanged Komodo could not find a way through the pawn wall. Komodo refused to acknowledge it was a draw, the game continued till move 197. A second minimatch win for Stockfish.

Games 7 and 8 were King's Gambit variants. There were many early exchanges in game 7 and only RB vs RN remained on move 24. Evals were low throughout the game and adjudication came quickly. Evals were low in game 8 as well. Komodo gave a knight to remove the black advancing pawns on the king side. The black king was exposed and Stockfish gave a rook for a knight to stop Komodo's attack, leading to a R vs NN imbalance. After stabilizing the queen side the engines agreed to a draw in a QR vs QNN position.

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