Wednesday, March 21, 2018

Season 11 premier division, after RR10

Crosstable after RR10

There were many draws in RR10, only 8/28 games were decisive. As a result not a lot changed in the table. Each engine has 14 games left to play, the standings haven't changed since Andscacs overtook Chiron in RR7 and will almost certainly will not change until the end.

A few interesting games

Chiron - Stockfish: Evals were close to 0 after the opening with an advantage for Chiron. The king side was open and Stockfish hid its king behind a white pawn. Chiron planned to advance rooks on the queen side, and it tried to exchange queens when Stockfish's eval jumped to almost 3. With a bishop and knight sacrifice Stockfish suddenly had a pawn on the 2nd rank with all the remaining white pieces unable to help. Chiron managed to block the passer for a while, allowing Stockfish to capture two pawns and get its rooks on the 2nd rank for the win.

Stockfish - Ginkgo: Stockfish had an eval advantage that stayed under 1 for the first 30 moves. Ginkgo's queen moved forward on the king side, evals started to increase when Stockfish trapped it partially. Stockfish traded down to a QR vs QR position, the material was balanced but the black pawns were weak and the king exposed. The game reached a queen ending with Stockfish 2 pawns up, an easy win.

Komodo - Fizbo: Fizbo pushed pawns on the queen side and Komodo pushed pawns on the king side. Komodo's king was exposed, yet it had an eval of 1 after it won a rook for a knight. Evals jumped over 3 when the king side opened and the black king was under attack. Fizbo tried to exchange pieces but Komodo was too strong, the game was adjudicated before it gained more material.

Andscacs - Komodo: Komodo was a pawn up early in the game, Andscacs had a strong center and a bishop pair as compensation. Evals became negative and increasing as the game progressed, Komodo punched a hole in the center and exchanged a bishop for a knight, the black pawn majority on the queen side became more important. Komodo created two passers, Andscacs gave a second pawn to get activity for its pieces but it was not enough. Komodo exchanged queens and pushed pawns on the queen side for the win.

Fizbo - Stockfish: Fizbo gave a pawn and opened a file on the king side to get an advanced passer. Stockfish captured a second pawn as Fizbo's queen attacked the back rank and pinned a knight. When Stockfish captured a third pawn Fizbo was desperate, and after Stockfish exchanged the pawns for a rook the game was over.

Ginkgo - Houdini: The game reached a drawn 6-man position, since Ginkgo doens't have tablebase support the game continued past move 120. Then the software running the game crashed, stopping the tournament for about an hour until it was restored (I saw all this later on the twitch archive). The game was adjudicated manually as a draw, there is a rule exactly for this case. The game itself does not appear in the TCEC archive.

Houdini - Fizbo: Houdini's king stayed in the center and hid behind an advanced passer. Fizbo's king was exposed in the king side, and the queen side rook and bishop were not developed. After exchaging queens Houdini created king side passers and captured two pawns. When the passers started marching towards the black king the game was over.

Stockfish - Andscacs: The engines were essentially shuffling from move 26. Stockfish had an eval over 1, it couldn't improve for 50 moves.The break came on the queen side, Stockfish created a passer that was well supported and Andscacs couldn't block it. The pawn got to the 6th rank, there Andscacs captured it and traded rooks. This opened files and allowed the white queen to move behind the pawn line. The black king was exposed in a QRN vs QRB position, the black pawns were vulnerable. Stockfish quickly exchanged down to a winning rook ending 3 pawns up.

Komodo - Chiron: Komodo had an eval advantage after the opening, Chiron's king was a little exposed on the king side with most pieces on the queen side. Evals kept increasing as the engines exchaged pieces, until only RN vs RB remained. The black bishop was trapped in the corner and Komodo's rook could attack both the black king and the weak pawns. It took a while but when Komodo started capturing pawns the game was over.

Featured game: Houdini - Fire
Premier division, round 70
Link to game on TCEC

The game reached a closed position on move 28, with most pieces and pawns still on the board. Houdini had an eval advantage and more space, the queen side and center were blocked. The king side pawns could move, but the engines chose to freeze the pawns and shuffle.

After exchanging bishops and shuffling for 30 moves Houdini captured a pawn on the queen side. A few exchanges later there were open files on the queen side and only QRN vs QRN were left.

The engines exchanged queens, and the evals were constant for a while. Fire took over the 2nd rank with its rook and exposed the white king, while Houdini cleared the queen side and created a connected pair of passers.

Houdini's eval started to increase quickly as it pushed the b pawn forward. After forcing a rook exchange the knight ending with a pawn up was winning for Houdini. Fire could stop the queen side pawns only at the cost of its king side.

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