Friday, November 17, 2017

Season 10, stage 2, RR 3

Table after RR 3:

An excellent RR for Houdini with 6/7 points, including wins against Fire and Komodo. It is firmly in the lead 1.5 points clear of Komodo and Stockfish. Stockfish also beat Komodo, and with a solid 4.5/7 is back to second place with good chances of getting to the superfinal. Komodo only got 3.5/7 in the RR, including two losses to its main rivals. These were its first losses of the season, and it will have to fight in the last RR to qualify. 

An interesting battle for 6th place is taking place, almost unnoticed. In the new format for season 11 the top 6 of stage 3 qualify directly to the top 8 stage (premier league?), while the bottom 2 will enter into the second league together with 6 other engines, only the two leaders of this league will continue to the top 8. Currently all four engines (Booot, Chiron, Ginkgo and Andscacs) are in danger, with Andscacs 0.5 points behind. Booot and Andscacs also have crashes that mean they automatically lose tiebreaks.

Some of the game highlights:

Stockfish - Andscacs: Stockfish had an eval advantage from the start. It then decided to sacrifice a knight in the center, leading to a long forced line that ended in a RB vs RB position 15 moves later. Stockfish was a pawn up with eval of around 1, but the bishops were of opposite color and the position was very drawish. After the rooks were exchanged it was obviously a draw, however the engines played on for more than 130 moves until they recognized that. 

Houdini - Fire: Houdini started with an eval advantage that grew to over 1 after a few moves. Houdini had much more space and a strong king side attack. More and more white pieces joined the king side and Fire had very little room to defend, the evals getting higher with every move. The game was adjudicated with tension at its highest, the PVs showed that Houdini was about to win material and that the black king would be in a mating net. Second loss in a row for Fire, Houdini 0.5 points ahead of Stockfish in second.

Komodo - Fire: Komodo outplayed Fire in the opening, getting an eval advantage of about 1. Fire countered through the open queen side, and after exchanging pieces the position was RB vs RB with opposite color bishops. The engines started shuffling, Komodo was a pawn up but it was a doubled pawn and the game was heading towards a 50-move draw. Komodo pushed pawns on the king side and Fire captured one, Komodo thought it was the wrong pawn and its eval started to jump. Now Komodo had a passer and its eval said it was clearly winning, but Fire was still holding. The 50-move counter was getting low and Komodo's eval came back down to 1 when Komodo found the right plan, bringing its king around to the queen side, sacrificing a pawn to reset the counter and attacking the f7 pawn. This time Fire could not defend and Komodo finally won the game. Incredible eval fluctuation, again Komodo manages to win in a drawn situation.

Ginkgo - Stockfish: The opening was balanced but Ginkgo played inaccurately, allowing Stockfish to take the initiative with evals increasing rapidly. The white king was vulnerable and under a black bishop threat. Ginkgo exchanged as many pieces as it could while the evals increased over 2. Stockfish's PV showed opposite color bishop endings, giving fans hope/fear of a draw. The game reached a BB vs BN position, and though Stockfish was two pawns up the evals remained constant for a while. Finally Stockfish found a winning line, though it was an opposite color bishops ending. Stockfish and Houdini are again with equal points.

Booot - Komodo: A fast repetition draw, only 24 moves.

Stockfish - Chiron: Another repetition draw, this time in 30 moves.

Houdini - Ginkgo: Houdini had an eval advantage after the opening. Ginkgo held on for a while, a pawn up, exchanging pieces and supporting a passer on the queen side. Houdini had a strong center. Ginkgo tried to open the king side and this allowed Houdini to block the center and put pressure on the black king. Houdini's eval increased rapidly, its major pieces very active on both sides. Within a few moves Houdini removed the black passer threat and was a pawn up in a winning QRN vs QRB position, with the black bishop trapped on the king side. Houdini ahead of Stockfish again.

Komodo - Andscacs: Komodo had a significant eval advantage after the opening, climbing to over 1. Andscacs' pieces were awkwardly placed, it had to accept a rook for knight exchange with evals over 2, and a RRB vs RBN position by move 26. Komodo then simply exchanged everything to get a winning king and pawns position. Easy win for Komodo, Andscacs has a chance in the reverse game.

Chiron - Houdini: The opening was balanced, after a while Houdini took the initiative and the negative evals started to increase slowly. Houdini opened a hole on the king side and put pressure with all its pieces. Chiron made a weak counter on the queen side, but Houdini's attack was strong with evals above 2. Houdini shifted to the center and was able to capture two pawns, exchanging down to a won double rook ending. At the end of round 18 Houdini is 1 point ahead of Stockfish.

Houdini - Booot: Houdini got a favorable opening and had an eval advantage. Booot tried to close the position and this worked for a while. Eventually Houdini found a way in, attacking first from the king side and then from the queen side. After a series of exchanges Houdini won a piece and reached a winning QB vs Q ending. Houdini is leading the table at the end of round 19.

Fire - Chiron: The opening was more or less balanced, a small eval advantage for Fire. Both engines developed pieces quietly with little contact between the pawns. When Fire started advancing pawns on the king side the evals began to increase. Chiron then chose a Q for RB imbalance, and with an exposed king had a hard time defending against Fire's queen and rook. Fire exchanged down to a QR vs RRB ending one pawn up and soon a second pawn, win for Fire.

Stockfish - Houdini: For a short while Stockfish thought it had a small advantage. Houdini equalized comfortably, both engines did not develop a serious threat. They exchanged pieces until only the kings were left in a drawn position. Four draws in round 20, no change in the table.

Houdini - Komodo: Houdini thought it had an advantage. For a while Komodo's eval remained low, but it started to increase when its king side became weak. After exchanging a pair of bishops Houdini controlled the king side. Evals climbed very fast as Komodo's king side crumbled, its king had to walk away. The game was adjudicated before Houdini started to win material. With this win Houdini extends its lead, will Komodo be able to win the reverse game?

Fire - Stockfish: Fire got a favorable opening, and evals gradually increased to 0.7 for Fire and 1 for Stockfish. Stockfish fans became very angry on the chat. They calmed down when the evals stayed at these levels and the engines began shuffling. Stockfish exchanged a pair of rooks and gave a pawn, leaving a QRB vs QRB position. All the pawns were on the king side and the extra white pawn was doubled. It took many moves and more exchanges but it was clear that Fire could not find a way to improve. The game ended in a drawn rook ending. At the end of the RR Stockfish and Komodo are level on points, 1.5 points behind Houdini.

Ginkgo - Chiron: Ginkgo had a significant eval advantage after the opening, which was eventually realized as a R for N advantage. However even with evals over 2 Ginkgo was unable to convert. It reached a R vs N endgame with only one pawn remaining, a 6-man tablebase draw. Ginkgo's lack of tablebase support was again its downfall.

Featured game: Stockfish - Komodo
Stage 2, round 19
Link to game on TCEC

This game was incredible for the fans, with a chess level that was way over my head - and I assume over most/all people's heads as well. After all these are chess giants using 43 cores to play.

Stockfish's eval started to increase after move 16, but as Komodo's eval remained low the feeling was that Komodo was confident in its defence. Stockfish's eval also came down a little, so probably false alarm.

The engines exchanged a few pieces and pawns, Komodo's king side became exposed and Stockfish had two connected passers. Komodo's central pawns looked strong, its eval stayed low. Who was right?

Both engines advanced their pawns, two pairs of connected passers marching in opposite directions. Queens were exchanged and it seemed the game was heading for simplifications. The game reached a RN vs RB position with Stockfish a pawn up. Evals were still at 1, and after two occasions of almost repetition draws, were there enough pieces on the board to convert?

Here Stockfish showed that it too has incredible endgame skills. The plan was to give the advanced h pawn for one of the queen side pawns, and then to use the fact that the bishop cannot help and that the black king is far away to get the second pawn. The maneuver was quite difficult to execute, it took almost 30 moves to complete, but when it was over the remaining white pawns secured a win for Stockfish. An amazing game which kept the fans wondering about the outcome for a long time. The first loss for Komodo, and without too much help from the opening. The reverse game will be very interesting to watch.

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