Wednesday, February 28, 2018

Season 11 premier division, after RR4

Crosstable after RR4

Stockfish is in the lead, already 4 points from 3rd place and well on its way to the superfinal. Houdini is second, now two points behind Stockfish after only 4/7 points in RR4. Komodo in 3rd is losing sight of the leaders after a disappointing 7 draws in RR4.
At the bottom Ginkgo continues on its sure path to relegation. Fizbo is still putting up a fight with 3.5/7 in the RR including 2 wins, one against 6th placed Andscacs.

A few interesting games

Komodo - Houdini: Komodo had an eval advantage which increased to over 1, but only got a RB vs RB ending with a pawn up, all pawns on the king side. Houdini held the position, Komodo could only get a draw, recall it lost this opening in RR3.

Fire - Ginkgo: Fire kept a small eval advantage for more than 45 moves. Evals started to increase after a series of exchanges reduced to a RB vs RN position, Fire with a pawn up and a queen side passer. Fire created a second passer on the king side and Ginkgo was forced to lose the knight to stop it, leading to a won RB vs R ending.

Andscacs - Fizbo: Andscacs traded a rook for a bishop and pawn early in the game. Fizbo's eval jumped to 1 and gradually increased as the engines exchanged pieces. The game reached a BB vs RN position, for a while the evals did not move. Fizbo then found a way to exchange a knight for a bishop and to get a winning 6-man position. Andscacs realized it was losing 20 moves later. An important win for Fizbo in its fight against relegation.

Stockfish - Ginkgo: There were many early exchanges with only RBN vs RBN left on move 25. Ginkgo had two weak pawns on the queen side and Stockfish's eval was over 1. After capturing a pawn Stockfish traded down to a winning N vs B ending.

Fire - Andscacs: The game reached an unusual material imbalance of RR vs BBN, evals remained low and the engines traded down to a drawn pawns vs B ending.

Fire - Chiron: The game started balanced in a closed position with a small eval advantage for Fire. When Chiron gave a rook for a knight and pawn the evals jumped over 1. After exchanging most pieces the game reached a R vs N ending, and the game was over after Fire created an advanced passer.

Houdini - Fizbo: Fizbo managed to keep the evals low for about 30 moves in a closed position. Houdini's eval went over 1 after it created a central passer, and evals continued to increase as the position opened up. Houdini slowly pushed the pawn forward, keeping it well protected, Fizbo could not stop it. Fizbo was about to lose a piece when the game was adjudicated.

Stockfish - Andscacs: Material was balanced in an open position, yet Stockfish's eval was over 1. Andscacs had a central passer, on the other hand its king was less protected. Stockfish pressed with its major pieces and Andscacs had to block attempts to infiltrate the back ranks. Eventually Andscacs traded down to a RN vs RN position but let go of its passer and Stockfish was a pawn up. Evals were high, the black pawns were all isolated. After Stockfish captured another pawn and created a passer the game was over.

Fizbo - Ginkgo: Fizbo's eval was over 1.5 in what looked like a closed position with both engines shuffling. However, when Fizbo opened the king side Ginkgo had to give a rook for a knight to get its king out of trouble. After exchanging queens only RBB vs BBN were left. Fizbo captured a pawn and reduced to an opposite color bishop ending, but with a pair of connected passers that were enough for a win.

Chiron - Fizbo: When the position opened up Chiron had two rooks controlling an open file on the queen side and a pawn up. Both kings were exposed on the king side, Fizbo had to defend against mating threats. With less pieces on the board the pawn advantage became more significant, the game ended in a QB vs QN position with Chiron about to capture a second pawn.

Stockfish - Komodo: Stockfish had an eval advantage of about 1 from the start. After the queen side opened the engines exchanged pieces and by move 38 only QBN vs QBN remained. Stockfish's eval peaked at 1.5, Komodo built a fortress it couldn't penetrate, more than 50 moves later the game ended in a draw.

Featured game: Chiron - Stockfish
Premier division, round 22
Link to game on TCEC

The game started in a closed position with evals close to 0. Stockfish had a pawn majority on the queen side while Chiron had an advanced central passer.

After the position opened up a little the engines exchanged almost all the pieces until the game reached an opposite color bishops ending with Chiron a pawn up. This is usually a drawish ending but Chiron's bishop was very weak and was blocked by its own pawns.

Stockfish captured the passer and then gave its bishop to create a connected pair of passers that Chiron couldn't stop. Stockfish won both sides of this opening.

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