Monday, April 22, 2019

Season 15 premier division after RR4

Crosstable after RR4

Stockfish and Leela continue to lead, Fire and Ethereal are still last. I doubt this is going to change in the remaining two RRs.

Komodo and Ethereal won their first game of the division, all engines have won at least one game. Stockfish and Leela have not lost a game yet. They are the only engines in the division with a positive score. The 4 engines in the middle of the table are tied, of the 24 games they played only two were decisive, both between Houdini and AllieStein with one win each.

Stockfish completed a double win against Komodo and against Houdini. This would have been surprising and unusual only a few seasons ago, now it seems quite natural. The "big 3" are no more, Stockfish and Leela are in a league of their own.

A few interesting games

Stockfish - Komodo: Stockfish had an eval advantage from the start, there was only one pawn exchange in the first 40 moves. Stockfish's eval increased over 1.5 when it opened the center. In a series of exchanges Komodo gave a knight for pawns and the game reached a RNN vs RB position on move 55, Komodo with two queen side passers. Stockfish was better in the endgame, it used the knights to block the passers and the black rook lines. After exchanging a knight for the bishop Stockfish started to capture black pawns and the game was adjudicated. A double win for Stockfish in this opening.

Leela - KomodoMCTS: See featured game below.

AllieStein - Houdini: AllieStein had an eval over 1 from the start. On move 20 AllieStein went a pawn up, its eval was over 2.5 yet its king was exposed and uncastled in the center. Houdini tried to attack but after exchanging queens the white king was relatively safe and evals continued to increase. AllieStein played slowly, with long shuffles and a few exchanges and pawn moves. On move 93 AllieStein sacrificed a knight temporarily, the game reached a RB vs RN position and the advanced connected passers on the queen side were enough for a win for AllieStein.

Houdini - Ethereal: Houdini pushed pawns on the king side and exposed the black king early in the game. Evals increased very quickly, Ethereal gave a knight and tried to get some counterplay with an advanced passer in the center. Houdini gave the material back and reduced to a QRR vs QRR position. The black king faced the white pieces with all files open, it had nowhere to run and the game was adjudicated on move 34.

Houdini - Stockfish: There were almost no exchanges, only a few pawns were removed after the start. Stockfish went a pawn up on move 32, its negative eval was over 1.5 but remained more or less constant for many moves. The engines mostly shuffled for 30 moves, Stockfish's eval started to increase just before the exchanges began. On move 64 the first piece was exchanged, by move 76 most pieces were gone and the engines reached a B vs R ending. The game was adjudicated a few moves later, a double win for Stockfish in this opening.

Komodo - Ethereal: The engines castled in opposite directions, Ethereal pushed pawns on the queen side and Komodo pushed pawns on the king side. By move 35 both engines opened a file near their opponent's king, Komodo was better and evals were over 1. Komodo's king side attack was strong and Ethereal scrambled back to defend. Ethereal gave a rook for a bishop to avoid mate and the game reached a QRR vs QRB position with evals over 3. The black bishop could not move, Komodo captured a pawn and created queen side passers, then reduced to a winning R vs B ending. This was the first win for Komodo in the division.

Ethereal - KomodoMCTS: KomodoMCTS played the opening badly, the black king was left without defenders and Ethereal developed a strong king side attack very early. KomodoMCTS gave a knight and tried to counter on the queen side, but it was too late. The game was adjudicated on move 32 with mate in the PV. This was Ethereal's first win in the division.

Stockfish - AllieStein: Stockfish had a small eval advantage from the start. AllieStein immediately regretted its 23rd move, Stockfish sacrificed a rook for a knight and both evals jumped over 4. AllieStein missed the combination that won Stockfish material, but it really gave up when it saw what happened. AllieStein gave all its pieces away, perhaps aiming for stalemate? Stockfish was a move away from mate when the game was adjudicated.

Fire - Ethereal: Fire created a central passer on move 24 and evals started to increase slowly. After a series of exchanges Ethereal captured the passer and the game reached a RN vs RN position on move 43 with Fire a pawn up. The endgame was slow, eventually Fire was able to create a passer and push it forward, this was enough to convert the win.

Featured game: Leela - KomodoMCTS
Premier division, game 86
Link to game on TCEC

Leela was better in the opening, its eval over 1.5 after a few moves. On move 20 Leela gave a pawn and created an central passer, then it pushed the passer to e6.

The engines exchanged pieces and Leela's eval increased quickly, it regained the pawn and its eval was over 4. KomodoMCTS had connected passers on the queen side, it used the pawns to block the center and didn't push them forward. After some shuffling Leela went a pawn up and the game reached a RBN vs RBN position on move 45.

KomodoMCTS traded its two passers to finally capture the white passer , Leela exchanged rooks and was 2 pawns up in a winning BN vs BN endgame.

The game was adjudicated 25 moves later.

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