Wednesday, March 7, 2018

Season 11 premier division, after RR6

Crosstable after RR6

With 6 RRs finished the division is at the halfway point. It is safe to say that Ginkgo will finish last, and that two of the leading 3 engines will qualify for the superfinal. It is likely that Fizbo will be the second engine to be relegated, and that Stockfish will be in the superfinal.

Stockfish continues to lead the table. The race for second place between Houdini and Komodo is close with 1 point separating the engines. In RR6 both engines scored 4.5/7. At the bottom Fizbo had another disappointing RR with 2.5/7, while Andscacs scored 4/7 increasing the gap to 4 points. Andscacs has caught up with Chiron, winning their head to head game in the RR.

A few interesting games 

Fire - Ginkgo: Fire had an eval advantage from the start. The evals slowly increased in a closed position while Fire prepared a king side attack. When the king side opened Ginkgo lost a bishop that was trapped there, Fire just exchanged everything to get a winning endgame.

Andscacs - Fizbo: In the game between 6th and 7th place Andscacs had an eval of over 1 after the opening. Fizbo gave a knight for pawns and countered with a connected pair of passers. Andscacs allowed a pawn promotion but gained material to get a QBN vs QR position, leading to a long shuffle and a draw.

Andscacs - Chiron: Andscacs pushed its pawns on the king side, Chiron felt the pressure and evals climbed quickly. Andscacs opened the king side with a knight for pawns sacrifice, Chiron could not defend its exposed king against the white pawns without losing significant material. With this win Andscacs moves further away from the relegation zone, catching up with Chiron in 5th position.

Fizbo - Fire: Fire took the initiative after a few moves, by move 31 it was a pawn up with passers on both the queen and the king side. Evals remained constant for 20 moves, then Fire found a winning line. After a series of exchanges only N vs B were left, Fire was two pawns up and winning. Not sure whether Fizbo blundered or Fire was winning all along.

Ginkgo - Komodo: The game was balanced until move 30, then Komodo sacrificed a pawn and opened the king side. The white king was exposed and Ginkgo gave a rook for a bishop to remove the immediate threat. Komodo was in control in the QRB vs QRR position, it took 20 more moves of slow improvement to complete the win. Komodo is now only 0.5 points behind Houdini.

Stockfish - Ginkgo: Ginkgo was up a pawn, while Stockfish had a strong queen side attack with a rook on the back rank. Stockfish's eval was over 2 in a QRB vs QRB position, it used its control of the back ranks to get the pawn back. Ginkgo had to give another pawn to free its bishop, Stockfish then traded down to a winning queen ending.

Fizbo - Stockfish: Stockfish's evals were over 1 in a closed position. For a while the engines shuffled and the evals drifted down, but then Stockfish found a winning line. It opened the center and after trading a rook for a bishop and exchanging queens it created a group of 3 central passers (one doubled). Fizbo's counter attack on the black king was not strong enough to prevent queening and a decisive material advantage.

Chiron - Ginkgo: Ginkgo's pieces had very little room to move, Chiron patiently organized its pieces and didn't open the position until it was ready. The evals increased all the time and were over 2.5 when Chiron opened the king side. Chiron continued to improve slowly, collecting pawns when it could, it was two pawns up with evals over 5. The game was soon adjudicated.

Houdini - Fizbo: Fizbo held the position for 40 moves, but when its queen moved forward alone on the queen side Houdini attacked through the center. Using the exposed black king Houdini was soon two pawns up and then it traded down to a winning rook ending.

Stockfish - Andscacs: Stockfish had a significant eval advantage from the opening. It slowly arranged its pieces for a king side attack while the evals increased. When it was ready Stockfish sacrificed a knight to open the king side, eval already over 4. Andscacs gave back a bishop and tried to hide its king behind a white pawn, but Stockfish had too many pieces aimed at the black king and Andscacs couldn't avoid losing material.

Komodo - Chiron: Chiron's king remained uncastled in the center, making it hard to develop the king side rook. Evals started to increase when Komodo dominated open files with rooks on both sides of the board. After exchanging queens Komodo was a pawn up. It then pinned a black knight on the back rank, eventually Chiron couldn't free the bishop or defend it, enough for a win for Komodo.

Fizbo - Ginkgo: Fizbo sacrificed a knight to open the king side. For a while Ginkgo's eval remained low, its king seemed to be relatively safe. Fizbo attacked through the center and pushed a passer to the 7th rank, Ginkgo gave the piece back and exchanged pieces, leading to a RB vs RN position. Fizbo was a pawn up and evals were climbing, it took another 20 moves for Fizbo to convert the win.

Ginkgo - Andscacs: The engines shuffled pieces with evals close to 0 until Ginkgo captured a pawn opening a file on the queen side. Andscacs' rooks used the open files to take over the queen side. This allowed Andscacs to capture two pawns, trade all pieces and get a winning king and pawns ending.

Stockfish - Komodo: Stockfish had an eval advantage after the opening, it chose to sacrifice a knight for 3 pawns very early in the game. Komodo's eval stayed close to 0 as the engines exchanged pieces. Stockfish's eval peaked at 1 but dropped quickly after the game reached a R vs RN position. Stockfish was 4 pawns up but couldn't get more than a draw.

Featured game: Houdini - Fire
Premier division, round 42
Link to game on TCEC

Houdini's eval jumped very early in the game, it saw an opportunity to be a pawn up. A few moves later Fire saw it too with a long PV agreement. At the end of the series of moves not many pieces were left, Houdini had a pawn majority on the queen side while Fire had a central passer.

Houdini chose not to exchange queens, after a few pawn moves the engines started to shuffle. Evals remained constant and Fire seemed to be holding. After 20 moves Houdini found a way to improve, it exchanged a pair of rooks and cleared the queen side for its pawns.

Houdini started to push its pawns forward and Fire had many threats to deal with: the king was in danger, its pieces were attacked, the white queen side passers became an immediate threat. The evals increased rapidly as Fire used up all its defences.

Fire had to give a rook for a knight to capture one of the queen side passers, the other passer reached the 7th rank. Fire launched a desperate QB attack on the white king, only to drive the king near its passer. Houdini was about to win more material when the game was adjudicated. 

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