Tuesday, March 13, 2018

Season 11 premier division, after RR8

Crosstable after RR8

Stockfish with 5.5/7 in RR8 extended its lead to 2.5 points over Houdini. Komodo is losing sight of the superfinal, it had another low score of 3.5/7 including two losses, the gap to Houdini is now 4.5 points.
Fizbo scored only 2/7 in RR8, the gap to Chiron in 6th is now 3.5 points. Andscacs is now firmly in 5th place, 1.5 points ahead of Chiron. Andscacs' win over Komodo was quite a surprising result.

A few interesting games

Chiron - Stockfish: The game was quiet for the first 30 moves in a balanced position. Stockfish's eval started to increase when it applied pressure on Chiron's weak pawns. Evals were over 1 when Stockfish used a gap in the pawn wall to penetrate with its queen and make threats on the king side. After some hesitation (two 2-fold repetitions in a row) and possibly Chiron inaccuracies Stockfish traded down to a QR vs QR position. Chiron had to give its queen for a rook to save its king, a win in black for Stockfish.

Andscacs - Fizbo: Material was balanced but Andscacs had a connected pair of passers on the queen side. When the passers pushed forward Fizbo was forced to give a knight to stop them, with evals over 1. The position was complicated with no pawns on the queen side and many pieces on the board. Fizbo traded Q for RN and tried to build a fortress for its king in a QRB vs RRB position, Andscacs broke through with a bishop sacrifice and its pawns marching towards the king won the game.

Chiron - Houdini: The engines castled in opposite directions, with the queen side open Houdini placed its pieces facing the white king. Very patiently Houdini increased the pressure with evals constantly increasing. After almost 30 moves Houdini was ready, finishing off with a queen sacrifice and a knight fork, leading to a won RR vs RN ending.

Komodo - Fizbo: Fizbo held a fortress for 50 moves, then Komodo found a way to break it. After a series of exchanges only QN vs QB were left, Komodo two pawns up with evals over 2. Komodo had no problem converting to a won queen ending.

Fire - Andscacs: Andscacs kept its king in the center, Fire was a pawn up with a potential king side passer. Andscacs tried to attack the white king but didn't have enough strength. Fire attacked the exposed black king from both sides and advanced its passer on the king side, causing Andscacs' position to collapse. The game was adjudicated before Andscacs lost more material. After 7 draws Fire finally wins a game against Andscacs.

Andscacs - Komodo: For the first 30 moves the game was balanced with all pieces on the board, Komodo controlled the only open file while Andscacs had a small eval advantatge. Then the engines exchaged a few pieces, Andscacs went a pawn up and Komodo's pawn structure was ruined on the queen side. Evals were over 1, but they remained constant for over 30 moves as the engines exchanged down to a RN vs RB position. There were no pawns on the queen side and the position looked drawish, especially after the game reached a rook ending. Then Komodo's eval jumped to 4 suddenly, and two moves later Andscacs saw that its advanced central pawns were strong enough to force a win. This was quite a shock, very unusual for Komodo to lose in such a way in an endgame, while Andscacs is not considered an endgame specialist and it does not even use tablebases.

Fizbo - Stockfish: Stockfish had an eval of about 1 when the engines started to shuffle on move 20. Nothing happened except a few pawn moves and exchanges, with the draw counter on 3 on move 100 Stockfish gave a rook for a bishop to continue playing. The position opened up a little and the shuffling continued. With the draw counter at 15 and both engines on increments Fizbo blundered the game away. Starting with a queen sacrifice and knight fork Stockfish reached a R vs N endgame with too many advanced pawns that Fizbo couldn't stop.

Houdini - Fizbo: Houdini activated its rooks early and Fizbo's king was stuck in the center, evals were over one by move 16 and kept increasing. Fizbo had to defend its king and block a queen side passer, while keeping its pieces safe. Eventually Fizbo's position collapsed, it lost a rook for a knight and its second rook was trapped. The game was adjudicated in a won QRR vs QRN position.

Stockfish - Andscacs: The engines castled in opposite directions and Stockfish attacked on the king side, evals increasing rapidly. Andscacs traded a rook for a bishop and two pawns, opening files on the king side. Stockfish's rooks and queen were very active, when Andscacs tried to block a file with a knight Stockfish traded a rook for it and shattered the black defence. Stockfish was soon up a piece and the game was adjudicated.

Komodo - Fire: Komodo took advantage of the uncastled black king and concentrated all its forces on the king side. Fire traded down to a QRR vs QRR position, Komodo used its pawns to open the king side. Fire had no counter and its king tried to run away to the queen side. Komodo's threat on the back ranks was enough to gain material and win the game. This is Komodo's first win against Fire in the division.

Fizbo - Ginkgo: Fizbo started with a rook for bishop trade and forced the black king to move uncastled. Then came a knight sacrifice and an all out attack on the black king. Ginkgo defended by exchanging everything, leading to a BN vs BN position with Fizbo a pawn up by move 30. In the endgame Fizbo's king was very active, Ginkgo didn't (or couldn't) stop it from penetrating the king side and isolating the black pawns there. Fizbo captured a another pawn and exchanged bishops, leading to a won knight ending.

Featured game: Stockfish - Komodo
Premier division, round 56
Link to game on TCEC

Stockfish had an eval advantage after the opening, Komodo's eval was closer to 0. Stockfish had a bishop pair which could be powerful, but the position was relatively closed with not so much room for the pieces to move.

After move 25 Stockfish's eval jumped over 1 as it pushed pawns on the king side. Komodo had a strong center and its eval remained low, it accepted Stockfish's pawn offer, losing a tempo and creating more room on the queen side. Meanwhile Stockfish opened a file on the king side and its eval was already over 2.

Komodo started to realize it was in trouble as more files were opened. The rooks and bishops had a lot more squares to move and the knights were too slow. Komodo gave the pawn back and exchanged queens but at this stage the evals were too high to have any hope of a draw.

The black king and pieces became targets for Stockfish's rooks and bishops, Komodo had no defence. The game was adjudicated as Stockfish was about to win material. Stockfish finally with a win against Komodo, now their head-to-head score is even after Komodo won in RR1. A second loss for Komodo in RR8.

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