Friday, September 9, 2016

Season 9, stage 3, RR 8

Final stage 3 table

Stockfish and Houdini qualify for the superfinal !!

Stockfish is still undefeated this season, as expected it won stage 3. Is this going to be Stockfish's season? So far it is in a class of its own.

Komodo could not close the gap in the last RR, it needed something extraordinary and one win against a bottom-4 engine just wasn't enough. The turning point was Houdini's win against Fire, after 7 drawn games between them. Looking at their performance Houdini and Komodo were very close, Houdini's single win over Komodo was the deciding result - compensating for the extra loss to Stockfish.

Houdini made a great jump in strength with this new version. Can it improve again for the superfinal? Will the new Stockfish release be even better? After the rapid tournament the superfinal begins, and we will see the final battle of season 9.

Some of the game highlights

Komodo faced Houdini in the first game of the RR, hoping to get a win and show Houdini fans that the opening bias caused Komodo to lose in the reverse game (Cato's fault?). The evals were in favor of white like before, but in this game the pieces were exchanged much faster. After 31 moves the game reached a rook ending, Komodo was a pawn up but it wasn't enough. With 3 pawns vs 2 on the queen side, the game was a theoretical draw. Does this mean Houdini is better? Which engine will reach the superfinal? Still 0.5 points between them and 6 games each to go.

Komodo and Houdini drew their games both playing black (against Fire and Andscacs, resp.), no change between them, now only 5 games to go. Andscacs managed to get a rook ending with two pawns against Houdini, but the pawns were f+h, a known 6-man draw.

Gull - Jonny: Jonny tried a knight sacrifice for two pawns early in the game, but did not have enough compensation. Gull was able to exchange pieces to a RRN vs RR position, and then go after the black pawns. The extra knight helped Gull to create a passer and win the game. A rare win for Gull in this stage, third win against Jonny though.

Stockfish had an easy win against Rybka. Rybka took a pawn and left its king almost defenseless, allowing Stockfish to develop a deadly attack. Rybka started to lose material and was a rook down with mate in sight when the game ended.

Komodo could not crack Andscacs' defense, only a draw against one of the bottom-4 engines. Qualification chances don't look good for Komodo.

Houdini and its fans had hopes of a win against Stockfish, the opening was quite biased and Stockfish won the reverse game. In the game Stockfish's defense proved to be very effective. Unlike the reverse game Stockfish playing black kept most of its pieces. The evals dropped to 0 by move 30 and stayed there until the end. Four games to go, still 0.5 points to Komodo, Houdini is getting closer.

Jonny - Fire was headed to a draw with evals at 0 when Jonny crashed. A bit disappointing that engines are crashing at this late stage of the season. Lucky that it happened in a game that has no impact on the qualification race. A crash in a game against Houdini or Komodo would have created a huge debate (fair or not, replay or not).

Komodo defended well playing black against Jonny, evals came down to 0 rather quickly and the game ended in a draw. Houdini played black against Gull, and for a while it seemed that Houdini had a chance with evals turning negative. Gull had a poor endgame performance this stage and there was a real chance it could blunder. Twice the evals got near 0.5, but in the end Gull held the draw. Three games to go, things are looking good for Houdini, Komodo is getting desperate.

Stockfish displayed its strength against Andscacs with a strong king side attack from move 20. Evals constantly increased as Andscacs tried to move pieces from the queen side. With the black king exposed Stockfish started to gain material, and the game was stopped before it was a full rook up. With a lead of 4 points Stockfish is sure to win the stage.

Komodo played against Stockfish with its back to the wall, but couldn't get any advantage in the game. Stockfish's eval was 0 after 15 moves and Komodo's eval stayed below 0.4 the whole game. Komodo is behind Houdini in SB score, it needs at least 1 point more than Houdini but it isn't winning at all so far this RR.

Houdini - Fire: see below. Houdini beat Fire and is now 1 point ahead of Komodo with two games remaining.

Rybka had a rook for knight advantage against Komodo, but Komodo was comfortable with eval at 0. When Rybka grabbed a pawn its rook was too far from the action and Komodo could attack the exposed white king, the evals started to turn negative. Rybka gave the material back but by then Komodo's connected passers were too strong in a bishop ending. Komodo's win in black gives its fans a final ray of hope, but they still need a Houdini loss.

Jonny had an eval advantage with a queen side attack against Houdini, but after a series of exchanges the evals came down and the game reached a drawn QN vs QB position. Houdini's 0.5 point lead should be enough for qualification with one game to go.

Komodo had nothing in the game against Gull, the game ended in a draw. This was Komodo's last game of the stage, it is tied with Houdini but loses the tiebreak. Houdini qualifies!! The remaning gmaes won't change this fact.

Stockfish had an eval advantage against Fire, right after Fire's first move. Fire's king stayed in the center and had to escape Stockfish's attacking pieces. Stockfish won a piece and reached a winning RN vs R position.

Houdini-Rybka was the last game of the stage. Rybka let Houdini develop a very strong king side attack so fast that the game ended before move 40 with Rybka sacrificing a queen and with both PVs showing mate soon. Now it is official, Houdini will meet Stockfish in the superfinal.

Featured game: Houdini - Fire
Stage 3, round 54
Link to game on TCEC

There were 7 draws between Houdini and Fire so far in the stage, the only engine pair with no decisive games. Houdini started with an eval advantage which grew to about 1 after 20 moves. Fire's eval was below 0.5 and it wasn't clear which engine was right, but there was a clear trend of gradual increase. At move 23 the two engine PVs agreed on the next 15 plys, unusual when the evals are diverging.

As the sequence of moves played out the evals started to climb again. Many pieces were exchanged and the position was simplified to RRB vs RRB. Houdini was a pawn up and had a doubled passer while Fire had a pawn advantage on the queen side.

The eval trend was unmistakable at this stage. Houdini wasn't winning yet but it didn't seem that Fire could hold. After more exchanges Houdini's advantage was clear. Fire's passer was weaker and slower, Houdini's rook made sure the black king cannot help, and the white passers looked dangerous. 

It took a few more moves for Houdini to get the win. This was the only decisive game for this engine pair after 7 draws, and with this win Houdini almost surely qualified to the superfinal. A 1 point lead over Komodo with two games to go against bottom-4 engines, as well as a tiebreak score advantage, should be impossible to beat for Komodo.

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