Sunday, August 28, 2016

Season 9, stage 3, RR 6

Table after 6 RR

Stockfish has extended its lead to 2.5 points after 4 wins in this RR including a second win against Fire, one of the toughest engines in this stage. It is very hard to imagine that Stockfish will not be first at the end of this stage, though there are 14 games left for each engine.
The race for second place is still very close between Houdini and Komodo. This may be decided only at the last game, as we saw in this RR. The final games for both the engines are playing white against weaker opponents, and unless one of them has a spectacular result we may not know which qualifies until the end of RR 8.

Some of the game highlights

Komodo - Houdini, again a draw. It seems the race will be decided by results against other engines.

Jonny couldn't get anything going against Stockfish, and Stockfish started to attack the white king with a queen and knights combination. Evals went Stockfish's way for a while but Jonny defended well and was only a rook for a bishop behind, evals becoming static in a QRB vs QRR position. After a long shuffle with a rook exchange and a few pawn moves Stockfish found a crack in Jonny's defense. Once the queens were gone the black king went after the white pawns and Stockfish had a won B vs R position. Stockfish's lead is 2 points again.

Fire reached a QN vs QB endgame with a pawn up after 21 moves against Gull. Gull held on for a while but after the queens were exchanged Fire was able to move all its pawns to dark squares, invisible to the black bishop, and Gull's position became totally lost. Fire's first win against Gull this stage.

Gull - Jonny entered a closed position early in the game and both engines shuffled for a long time. Gull was ahead on eval so it was unexpected when Jonny moved pawns and reset the 50-move counter. Evals started to jump and Gull won a pawn, but the engines started to shuffle again. This time it was Gull who moved a pawn, causing black's position to open and eventually winning a knight and the game. This was Gull's second win of the stage, and first time it won a pair of reverse matches. Both wins were against Jonny.

Stockfish had an easy game against Rybka, with a big eval advantage and a rook for a bishop already at move 20. Evals continued to increase while Rybka lost a piece, Stockfish with a rook advantage is too strong.

Komodo - Andscacs was the reverse game of Komodo's loss in the previous RR. Andscacs held on for about 30 moves with a small eval advantage for Komodo. With a pawn sacrifice Komodo initiated a series of exchanges, after which Komodo's pieces were much stronger than Andscacs' and the evals were over 2. The RN vs RN ending started with equal material but after a while Komodo was a pawn up. The white king was very active in the center as a third piece. The game ended with Andscacs facing material loss and queening by white. Komodo got its revenge.

Houdini didn't get its revenge on Stockfish. Stockfish equalized quickly and exchanged pieces until a draw was declared. Houdini and Komodo are tied again after 3/7 games of this RR.

Rybka - Gull was quite dull for about 50 moves, reaching a RB vs RB ending which seemed like a dead draw. Then Gull allowed Rybka to exchange rooks, and suddenly Rybka had a big advantage since Gull's pawns were targets for the white bishop while Rybka's pawns were safe. It took a while but the black pawns started to fall and Gull realized it was lost. This was Rybka's first win of a reverse pair of games.

Fire - Rybka set a new length record for the stage: 205 moves, 6:40 hours of waiting for a draw.

Komodo couldn't penetrate Stockfish's defense, Houdini had hope for about 25 moves against Fire. Only 2 games per engines left in this RR, Komodo and Houdini still tied in second place.

Jonny started with an eval advantage against Houdini, but Houdini equalized quickly and took the initiative. Jonny had a bishop pair that could hardly move, while Houdini's knights were very active on the king side. Houdini exchanged a knight for a bishop to clear the white king side pawns and gain a passer on the 3rd rank. Jonny had to give a piece to take out this threat, leading to a RB vs RBN position which Houdini won. Once again Houdini leads Komodo by 0.5 points, one game left in the RR.

Komodo - Gull (game missing from archive, used chessbomb to review game but it's hardly the same): Komodo sacrificed a pawn and a rook for a knight but got a strong attack against an uncastled king. Gull gave the material back but its king was trapped and Komodo had two passers. Komodo had no problems converting its advantage to a win.

Stockfish - Fire started with an eval advantage for white with evals close to 1. For a long time evals remained almost constant while the engines exchanged pieces. The games reached a RRN vs RRB position with Stockfish a pawn up, all the pawns on the king side. Stockfish's eval started to move after move 50, and one pair of rooks was traded. The endgame was very hard for me to understand. Stockfish was able to put pressure on the black king, and the evals really jumped after Fire moved a pawn to avoid mate. This created a passer for Stockfish and the game was over.

Houdini - Rybka: Rybka held for about 20 moves before Houdini's eval started to increase. After the center was cleared Houdini had a passer. Most pieces were exchanged and in a Q vs RR position Rybka had to give a rook to stop the pawn, leading to a won position for Houdini. The last game of the RR and Houdini is back in second place, 0.5 points ahead of Komodo.

Featured game: Stockfish - Andscacs
Stage 3, round 39
Link to game on TCEC

The pieces to watch in this game were the white knights. Right from the start they made a stand on the queen side, a bit off center but still interfering with black's development.

Andscacs' queen tried to do something on the king side, Stockfish drove it to a weak square on the side. Meanwhile the white knights moved to the center, one following the other mutually guarding each other.

Stockfish now went after the queen side, opened it up and won a pawn. Andscacs could not get enough defenders around and constantly had to watch out for forks and discovered checks. 

Stockfish tried to exchange pieces, and with less pieces on the board the knights could seperate and be more active. One knight was involved in threatening the black king while the other put pressure and later won a second pawn.

After the queens were exchanged the white knights made sure the black king would remain in its corner and it was just a matter of time before Stockfish's extra pawns became dangerous, winning the game.

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