Monday, September 10, 2018

Season 13 premier division after RR1

Crosstable after RR1

Stockfish is leading the table with a +3 score and no loss, including a win against Komodo. Komodo is the only other engine with a positive score of +1. Houdini is the only other engine with no loss, it drew all the games in the RR.
Chiron is last with a score of -2, there is a good chance it will be relegated back to division 1. Ethereal has a 0 score so far, two wins (one against Fire) and two losses. It is quite possible it will survive this division.
Some of the openings were biased and it should be interesting to see the results of the reverse games in the next RR.

A few interesting games

Andscacs - Ginkgo: Andscacs pressed hard in the opening game. Its eval peaked over 1.5 despite being down an exchange. Ginkgo managed to stop connected passers, one on the 7th rank, in a QB vs QR position. The game ended in a draw.

Ethereal - Fire: Ethereal came out of the opening a pawn down but with an advanced passer in the center and increasing evals. Ethereal exchanged pieces, giving a rook for a bishop as well. The game reached a BB vs RB position, Ethereal 3 pawns up. Fire traded the rook to force an opposite color bishop ending, still Ethereal found the win. Ethereal with a win in its opening game, how far can it go in the premier division?

Stockfish - Komodo: Featured game, see below. 

Ginkgo - Komodo: Komodo gave a bishop for two pawns early in the game. Ginkgo's king was exposed, Komodo did not attack and the engines shuffled for 20 moves. It seemed Ginkgo lost its patience, the position opened up and the engines exchanged queens, with evals increasing in favor of Komodo. Ginkgo's position collapsed, the game was adjudicated after Komodo won a piece and was 3 pawns up.

Fire - Chiron: Chiron moved its queen forward and Fire almost trapped it. By the time the queen found safety Fire attacked the back rank and black king with its rooks and queen. Fire won a bishop and the RN vs R ending was won for white.

Andscacs - Ethereal: Ethereal's 24th move led to a long series of exchanges and a RB vs RN position on move 36. Andscacs was two pawns up with eval over 1.5 and increasing. Ethereal tried to hold against two white passers, it managed to capture one but allowed Andscacs' rook to move forward and attack the black king. Andscacs found a way to exchange rooks and advance its king, winning the B vs N endgame.

Fire - Komodo: Fire was up a rook for a knight in a closed position. The engines shuffled for a very long time, both had very little time when Fire played several inaccuracies after move 98. The game reached a RRB vs RBN position with a pawn wall across the board. Only the black pieces could move freely, Komodo patiently maneuvered until it captured two pawns. Fire's position collapsed and the game was adjudicated.

Andscacs - Stockfish: Andscacs thought it was ahead when Stockfish's eval turned negative on move 31. The engines castled in opposite directions, Stockfish opened a file on the queen side with doubled rooks facing the white king. Andscacs traded Q for RB and the game reached a RBN vs QN position. It took Stockfish another 30 moves to win but there was never doubt it would.

Ethereal - Chiron: The engines castled in opposite directions, Ethereal pushed pawns on the king side towards the black king. Chiron exchanged pieces and gave a knight for pawns to open the queen side and counterattack. The game reached a RRB vs RR position, Chiron's king was trapped in the corner and the engines started to capture pawns. The game was adjudicated just before Chiron lost its last pawn.

Stockfish - Ethereal: The engines shuffled in an closed position and didn't seem to make progress. On move 45 Stockfish saw an opportunity and pushed pawns on the king side. After a long series of exchanges the game reached a RN vs R position, Stockfish converted the win without difficulty.

Komodo - Chiron: Komodo started a king side attack with a bishop sacrifice. After almost all pieces were exchanged Komodo was two pawns up in an opposite color bishop ending. Chiron held the draw but it took more than 200 moves before the evals were low enough to adjudicate. 

Featured game: Stockfish - Komodo
Premier division, round 1
Link to game on TCEC

Stockfish's eval was over 1 after book, Komodo's eval remained mostly under 0.5. Stockfish gave a pawn to open the queen side. The position was unstable, with Komodo threatening a fork with one knight, Stockfish threatening to take the other knight, the b4 pawn pinned and rooks facing each other on the d file.

There was a series of exchanges that resolved the tension. Stockfish was ahead by a knight for 2 pawns and Komodo had connected passers on the queen side. Evals increased very slowly, Stockfish's eval was close to 2 while Komodo's was still under 1. There was a long PV agreement and it wasn't clear whether Stockfish could convert.

The engines followed the PV line and the game reached a QBN vs QB position on move 33. The pieces moved around and evals did not change a lot, on move 44 Stockfish exchanged queens.

Evals were almost constant for a very long time, and the endgame was very slow. Stockfish's bishop made sure the queen side pawns did not advance. In the end Stockfish moved its king forward and this broke Komodo's defense. Can Stockfish hold the reverse game?

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