Sunday, September 16, 2018

Season 13 premier division after RR3

Crosstable after RR3




Stockfish is firmly in the lead after scoring 6/7 in RR3, including a second win against Komodo. Houdini drew all its games in RR3 but is still second, Komodo with 4/7 closed the gap to only 0.5 points. Ethereal lost once in RR3 and is now a point behind Fire in the race for 4th place. Chiron and Ginkgo close the table, Andscacs is a point clear of the relegation zone.


A few interesting games

Stockfish - Komodo: Komodo sacrificed a pawn on the queen side and attacked the white king side. The game reached a NN vs R imbalance, and Stockfish's eval started to increase. It advanced a queen side passer to the 6th rank. Komodo avoided exchanging queens for a while, when Stockfish forced the exchange only RBN vs RR remained and the game was adjudicated. A second win for Stockfish against Komodo in the division.

Ginkgo - Komodo: Ginkgo traded its queen for two rooks and the game reached a RRB vs QN position. Evals turned negative and gradually increased as Komodo outplayed Ginkgo. Komodo captured all the white pawns and was 3 pawns up when the game was adjudicated.

Houdini - Stockfish: Houdini was up a rook for a knight with an eval advantage, Stockfish reduced to a RR vs RN position and held the draw.

Andscacs - Stockfish: Evals turned negative over 1, Stockfish captured two pawns and created a queen side passer. Andscacs equalized material while evals continued to increase, after several exchanges only RB vs RN were left. Stockfish was two pawns up again and Andscacs' advanced passer was not strong enough. The game was adjudicated with Stockfish 4 pawns up.

Stockfish - Ethereal: The game reached a QRR vs QRR position with evals at 0. Evals started to increase on move 50, Stockfish calculated better than Ethereal. Stockfish opened the queen side and created a queen side passer. The combination of an advancing passer and threats on the exposed black king were enough for Stockfish to win. The game was over before Ethereal lost material.

Chiron - Stockfish: See featured game below.

Stockfish - Ginkgo: Evals were close to 0 for 35 moves in a closed position. Ginkgo's king was in the center uncastled, Stockfish gave a pawn and exchanged pieces, its eval jumped over 2.5. Then Stockfish created a king side passer in a QNN vs QBN position. After queens were exchanged Ginkgo was forced to lose a piece for the passer, leading to a won NN vs N endgame.

Komodo - Chiron: Komodo had an eval advantage of about 1 in a closed position. Chiron kept the evals under control for more than 40 moves. Komodo gave a pawn in a QRR vs QRR position and opened files, then Chiron blundered on move 46 and Komodo's eval jumped over 3. Komodo took over the 7th rank, exposing the black king to mate threats. It took a while for Chiron to realise it was losing.

Featured game: Chiron - Stockfish
Premier division, round 20
Link to game on TCEC

The engines castled in opposite directions, Stockfish pushed a pawn on the queen side and weakened the white king's defense. Then Stockfish sacrificed a pawn and a bishop and exposed the white king completely. Evals were negative though Chiron was a piece up.


King safety was a major concern for Chiron while Stockfish's king was safe in its corner. Stockfish drove the white king to the 7th rank and placed all its major pieces on the back rank. Analysis by Stockfish thought Chiron could still hold, until Chiron's 45th move.


Stockfish's eval jumped over 5, and Chiron's eval followed immediately. Stockfish pinned the white knight and together with mating threats and an advancing passer forced Chiron to trade a queen for a rook.


In the RRN vs QR position Chiron needed all its pieces to defend its king and Stockfish had time to capture the remaining white pawns on the king side before the game was adjudicated.

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