Friday, September 2, 2016

Season 9, stage 3, RR 7

Rapid tournament announcement - Anton (TCEC director from chessdom) announced that after stage 3, instead of the superfinal, there will be a rapid chess tournament. All 32 engines that participated in the season will play a double RR, with 25 min + 10 sec time control. The superfinal will start after the rapid tournament, somewhere in October.

I must say I was a little disappointed. Who asked for this change? Anton claimed popular demand, not sure who these people are. I know some people complain about the long TC, boring games etc. I'm sure others will now complain about the short TC. 992 games, 20 games a day is too much. That's more games than the regular season. And why now and not after the superfinal? Waiting for better hardware? Someone suggested that this will allow Houdini to get a better version - if it qualifies to the superfinal.

In any case, I will not be following this event closely. It's impossible for me to cover that many games. I may post a statistical report after the event is over.

Now, back to normal TCEC. 

Table after 7 RR

Another solid RR for Stockfish with 3 wins, one of the wins against Houdini. Stockfish is still undefeated not only in the stage but for the whole season, impressive.  Stockfish will be in the superfinal, with a 3.5 point lead over Komodo in third place and 7 games to go.
Houdini started with a win against Komodo, boosting its qualification chances. This was later offset by the loss to Stockfish, but still Houdini is in second place with a lead of 0.5 points. Komodo clawed its way back, but it still needs a good last RR. A lot depends on the Komodo - Houdini reverse game, the first game of RR 8.

Some of the game highlights

Houdini - Komodo: What a start to the RR, after 6 draws and only two direct matches left between the engines. The evals were high out of the opening, good for Houdini, trouble for Komodo. There was not a lot of change in evals for 50 moves, Houdini kept the pressure, Komodo defending but looking good. Time was running out for both, especially for Houdini. And then without warning, with less than two minutes remaining, Houdini's eval took off. The strange thing was that Komodo saw its problem at once (why did it allow the position or evaluated it so low before?). With no time to think Houdini was able to reach a queen endgame with a pawn advanage, create a passer and find a win. Amazing. With this win Houdini is 1.5 points ahead of Komodo, its qualification chances much higher. Can Komodo beat Houdini in the rematch?

Stockfish had control of a long diagonal and used it to drive Jonny's king out of the corner to the center of the board. Then through a combination of mating threats, pins and a pawn on the 7th rank Stockfish gradually improved its position in a QRB vs QRB position. Jonny was a pawn up but was too busy defending to advance the queen side pawns. The game was over just as Stockfish was about to win a piece after queening a pawn. A good start for Stockfish in the RR, keeping its 2.5 points lead.

Jonny started with an eval advantage against Gull, but Jonny tends to exaggerate and can't be trusted. At some point Jonny trapped a black rook on the queen side and started a pawn storm on the king side. After a series of exchanges Jonny's eval was at 3 in a QBN vs QRN position two pawns up, with a paralyzed black rook. After queen exchange the white pawns took over, Gull lost a piece and the game was over.

Houdini didn't get a lot out of the opening against Andscacs, but Andscacs made two mistakes: it allowed Houdini to create a passer and it sent its queen to chase two poisoned pawns on the queen side. By the time the queen came back the white passer was almost unstoppable, and evals were close to 4 as it reached the 7th rank. Andscacs gave a rook for the pawn and Houdini won the game easily. Houdini now 2 points ahead of Komodo, fourth win in a row for Houdini.

Stockfish - Houdini: Stockfish won !! (see featured game below). Houdini 1.5 points ahead of Komodo.

Komodo's evals stayed at around 0.5 for 30 moves against Jonny. Just as Komodo's bishop pair started to take hold of the center Jonny chose to give a rook to take out one bishop. Komodo welcomed this exchange, and after more exchanges reached a R vs N ending which was easy to win. First win for Komodo this RR, it need more to have hope of closing the gap to Houdini.

Houdini started with an eval advantage against Gull, and Gull held out only 20 moves before the evals started to rise. Most of Gull's pieces were ineffective on the queen side, while the black king was in danger on the other side. Through a clever series of exchanges Houdini created a RPPP vs BN imbalance, opening up the king side and exposing the black king. This led to a RB vs RN position with Houdini 3 pawns up, it took a while but the win was clear. Gull added a little joke, evaluating the final tablebase win at 0.61. The gap to Komodo is still 1.5 points, Houdini matching every Komodo win.

Stockfish, playing black against Andscacs, was able to take the initiative. It was not enough for a win though, but Stockfish can afford to draw as black. It has a 4 points cushion to Komodo in third, and only 10 games remaining.

Stockfish - Komodo was a draw. Komodo needs wins but it probably won't win black against Stockfish. It has some hope for the reverse match.

Gull surprised Andscacs (and most everyone else) with a win. It started with a modest advantage and gradually increased it. Gull gave a rook for a knight, and later this turned into a BN vs R imbalance. After queens were exchanged the white bishop pair took over the center, and a passed pawn cost Andscacs a piece. Andscacs still had 3 extra pawns in a RBB vs RB position, but after all pawns were gone Gull did not blunder the ending for a change.

Fire - Houdini was another draw, seventh draw for these engines in this stage. Houdini had no problems in black against a tough opponent. No change in the lead over Komodo.

Komodo - Rybka: after 20 moves Komodo sacrificed a pawn to get a deadly king side attack. As a result Komodo won a piece and reached a winning RN vs R position. Komodo putting some pressure on Houdini.

Houdini seemed to be on a sure path to victory against Jonny, keeping an eval advantage of 0.8 for 30 moves. A first signal that Houdini was confused was the dance the white knights performed on the queen side, moving forward and coming back with no purpose. After a series of exchanged of pieces and pawns the evals started to come down. In the end the game reached a drawn rook ending. The gap to Komodo is now 1 point with one game per engine left in this RR, both with black. Is Komodo coming back?

Stockfish took over the game against Gull with evals rising after 20 moves. There was nothing spectacular, just a better position that led to a rook ending with Stockfish a pawn up and pawns on both sides of the board. Stockfish improved to 3 pawns advantage and then it was just a formality to get the win.

Gull thought for over 51 minutes on its second move after book against Komodo. That was quite unusual, and also did not change the eval, what was Gull thinking so much about? Then on move 18 the experts on the chat claimed that Gull missed a move (18. Ng5), an attack that would have given it a big advantage if played correctly. Komodo also missed this, was it real or not? Anyhow, as the game continued to a RN vs RB ending Komodo took the initiative. Gull's endgame abilities were no match for Komodo, after rooks were exchanged Komodo grabbed two pawns and got the win. Komodo finishes the RR with a win in black, can Houdini do the same?

Rybka was a pawn up against Houdini, and it didn't let go of the advantage. Houdini easily got a draw but no more than that. The game continued for a long time since Rybka misevaluated a drawn 6-man position, thinking it had a clear advantage. The gap between Houdini and Komodo is back down to 0.5 points, same as the gap after the previous RR.   After all the excitement we've had the race is still the same, only one RR to go.

Featured game: Stockfish - Houdini
Stage 3, round 45
Link to game on TCEC

Stockfish had an eval advantage of about 0.8 out of the opening, quite a lot. By move 18 It was a pawn up, but there were so many exchanges that only RRB vs RRB remained. The position looked very drawish, and with opposite color bishops as well.

For a very long time the engines developed their pawns and tried to find the best squares for their pieces. The evals did not change a lot, a little bit higher than before.

Stockfish attacked on the king side and was able to capture a second pawn and get a passer. The price was exchanging a pair of rooks. A RB vs RB position with opposite color bishops could be a draw after another rook exchange, even with two pawns advantage. Could Stockfish pull this off?

The target was the pawn on b7, but it was defended by a bishop and could only be attacked by the rook. Houdini used its rook to threaten the king side pawns so that the white king would stay and protect them. Stockfish then found a way (Houdini blunder?) to get the king involved, and the evals shot up.

With the king going to b6 Stockfish could give a rook for a bishop as well as two pawns to take out the black pawns, that would be a winning BPP vs R position. Houdini had nothing to do against this, and the game was over in a few moves. Stockfish and Komodo fans were delighted, although Houdini still has better chances in the race for the superfinal.

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