Season 13 premier division after RR7

Crosstable after RR7


Komodo continued its run in RR7, scoring 5/7 including a win against Houdini and a loss to Stockfish. it extended its lead over Houdini to 2 points. Stockfish is sure to finish the division in 1st place, it has practically qualifed to the superfinal already. At the bottom Andscacs is 1.5 points above the relegation zone, Chiron and Ginkgo need a miracle to survive.


A few interesting games

Chiron - Houdini: Chiron had an eval advantage from the start, Houdini turned the game around and evals became negative. Houdini created a queen side passer and pushed it to the 3rd rank. Evals started to increase after queens were exchanged, Chiron stopped the passer from advancing in a RBN vs RNN position. It took Houdini a while, but eventually its pieces surrounded the passer and forced Chiron to lose material.


Stockfish - Komodo: Stockfish had an eval advantage from the start. Its eval jumped over 1.5 after the king side opened and it went a pawn up. At first all pieces moved to the king side, and both engines did not attack. Then Stockfish opened the queen side where it had a pawn majority. Evals started to jump when Stockfish created a queen side passer and pushed it to the 7th rank. Stockfish reduced to a QR vs QR position and captured another pawn, enough for adjudication.

Ginkgo - Komodo: Ginkgo started with a small eval advantage, the engines exchanged most pieces and the evals turned negative. Komodo gave a rook for a bishop and pawns, the game reached a RB vs BN position with Komodo two pawns up. Komodo had a pawn majority on the king side, Ginkgo gave a pawn to break the black pawn line. Komodo then outplayed Ginkgo in the ending, though it took almost 40 more moves. The black pawns slowly advanced with the black pieces supporting, the game was adjudicated with a pawn on the 3rd rank.

Fire - Chiron: Fire was up a rook for a bishop early in the game. All of Chiron's pieces were on the queen side when Fire created a passer on the king side. Chiron had a passer on the queen side, but Fire had the back rank covered. Chiron had no rook to cover its back rank and the white passer was enough for a win.

Chiron - Andscacs: Chiron had an eval over 1 for a while. The game reached a BN vs BN position with Chiron a pawn up, it wasn't enough for a win. Chiron missed a rare opportunity to win and improve its chances of avoiding relegation.

Stockfish - Fire: The engines shuffled more than 60 moves, Stockfish's eval was over 1 but nothing was happening on the board. Evals started to increase when Stockfish pushed pawns on the king side and opened the position. The black king was in danger and Fire exchanged pieces until only RN vs RN remained. Stockfish's rook had control of the 7th rank and it could attack the black pawns from the rear. The game was adjudicated when Stockfish was two pawns up and was about to gain more material.

Komodo - Houdini: See featured game below. Houdini's first loss in the division.

Chiron - Ginkgo: Evals jumped to about 1 early in the game, Ginkgo had weak dark squares after it lost its DS bishop. Chiron used a mate threat to win a rook for a bishop. The engines exchanged pieces until only R vs N remained, an easy win for Chiron. Only Chiron's second win, still fighting against relegation.

Stockfish - Ethereal: The engines castled in opposite directions. Ethereal's queen side was under threat, its king exposed through the light squares and the black DS bishop was trapped in front of the pawns. Stockfish attacked through the center and the evals jumped very quickly. The game was adjudicated before Ethereal lost material.

Komodo - Andscacs: Komodo was a pawn up with a queen side passer, evals went over 1.5 as Andscacs tried to block the passer and Komodo exchanged pieces. In a RBN vs RBB position Komodo pushed the passer to the 6th rank. Andscacs's pieces were busy defending the queen side and Komodo captured a pawn on the king side to create a second passer. The game was over a few moves later.

Stockfish - Ginkgo: Stockfish gave a pawn and opened the king side a little. The center was blocked and too many of Ginkgo's pieces were on the queen side. Ginkgo gave a rook for a bishop, not enough to stop Stockfish in a QRR vs QRB position. The black king was exposed and after exchanging queens Stockfish started to capture black pawns. Ginkgo's rook made checks that only delayed the end.

Komodo - Chiron: Chiron's king was exposed with most black pieces on the queen side. Komodo gave two pawns, doubled rooks on the open g file and sent all its pieces to attack on the king side. Chiron's defense collapsed quickly, the game was adjudicated before it lost material.


Featured game: Komodo - Houdini
Premier division, round 45
Link to game on TCEC

Komodo had a small eval advantage from the start. Houdini had a pawn majority on the queen side and it pushed those pawns forward. When Komodo tried to break the black pawn line Houdini initiated a series of exchanges that resulted in a R vs BN imbalance. Komodo's eval jumped over 1.


Komodo kept its pieces on the queen side, for a while there was no change in evals and the engines seemed to make shuffling moves. Komodo's eval jumped over 2 when Houdini moved its king side pawns and the king side opened.


Komodo's queen shifted to the king side and attacked the black king through the hole in the pawn line. Houdini's pawns were vulnerable and Komodo started to capture them. After clearing the black pawns on the king side Komodo exchanged queens, it was 3 pawns up already.


The game reached a RR vs RBN position with Komodo 4 pawns up and Houdini's king exposed. Adjudication was only a matter of time.

Season 13 premier division after RR6

Crosstable after RR6


In RR6 Komodo made a comeback with a score of 5.5/7 including a win against Stockfish. It is now in 2nd place, 0.5 points ahead of Houdini which only scored 4/7. This was the only significant change in the crosstable, Fire is still ahead of Ethereal in the race for 4th place, Andscacs is still ahead of Chiron and Ginkgo in the race against relegation.


A few interesting games

Komodo - Stockfish: See featured game below. First loss for Stockfish in the division.


Komodo - Ginkgo: Komodo took over the game from the start. It castled long annd pushed pawns on the king side. Ginkgo kept its king in the center and attacked the queen side, after a long series of exchanges only RRB vs RRB remained with Komodo a pawn up on move 28. Komodo was soon 3 pawns up in a won bishop ending. Back to back wins for Komodo.

Stockfish - Houdini: Stockfish's eval jumped over 1 but was very unstable. The king side opened and both kings were exposed. Houdini gave a rook for a bishop and pawns, it had two central passers which countered Stockfish's king side attack. Houdini reduced to a QR vs QB position, and though Stockfish captured the black passers Houdini was able to hold a draw. After this game Komodo and Houdini are both in second place with a +8 score.

Chiron - Fire: Evals turned negative early in the game. Fire gave a rook for a bishop and created a pair of connected passers on the queen side. The passers advanced all the way to the 2nd rank, and Chiron was forced to lose a piece to stop them. The game ended in a QB vs QBB won position for Fire.

Komodo - Fire: Evals started to increase on move 30. Komodo had doubled rooks on the open d file and its two bishops targeted the black king in the corner. Komodo attacked through the center, went two pawns up and created a central passer. A series of exchanges, including a pawn queening, reduced to a RR vs R position. After this win Komodo is in 2nd place, 0.5 points ahead of Houdini.

Stockfish - Andscacs: The game reached a RNN vs RR position on move 31. Stockfish gave 3 pawns and concentrated its efforts on keeping a central pawn alive. Evals jumped when the white knights moved forward on the king side, supported by the pawn. A combined attack on the black king and pawns allowed Stockfish to push its pawn to the 7th rank and drive away the black king. Andscacs had 5 pawns, one on the 2nd rank, not enough after Stockfish queened.

Houdini - Andscacs: Andscacs' problems started when it moved a knight to the edge with no way to retreat. Evals increased over 2 as Houdini exchanged the knight and trapped a bishop in the same square. Evals were over 3 when Houdini captured the bishop, Houdini then reduced to a won bishop vs pawns ending.

Komodo - Ethereal: Ethereal pushed pawns forward and won a rook for a bishop, yet Komodo's eval was over 1 and increasing. Komodo blocked the black pawns, making the white rooks less effective, and then targeted Ethereal's weak pawns. It took a while but Komodo managed to capture a pawn and create a pawn majority on the queen side. After clearing the way Komodo's pawns were unstoppable, securing the win. Komodo keeps its lead over Houdini.

Stockfish - Chiron: Only RBB vs RBB remained on move 26. After exchanging a pair of bishops the black pieces were very passive and could only defend the pawns. Stockfish moved its rook to the king side and its king to the queen side, the game ended with Chiron in zugzwang and forced to lose a pawn, its defense collapsing.


Featured game: Komodo -Stockfish
Premier division, round 36
Link to game on TCEC

Komodo had an eval advantage from the opening that increased slowly. Stockfish kept its king in the center and exchanged pieces, only RB vs RB remained on move 29, Komodo a pawn up and evals over 1.


Evals stayed more or less the same as the engines stabilized pawns on the king side and in the center. Komodo used the pawn majority on the queen side to create passer.


Komodo exchanged rooks and reduced to an opposite color bishop ending. Under usual circumstances this would be a drawn ending, one pawn is not enough for a win. However,  evals started to increase quickly. Stockfish gave a second pawn to stop the white king from penetrating the center.



Komodo gave a pawn back to create a second passer on the king side. Stockfish could not cover both sides and keep the white king away, the game was adjudicated with a Komodo win.

 

Season 13 premier division after RR5

Crosstable after RR5


There were only 6 decisive games in RR5 and there were no changes in the standings. Stockfish extended its lead to 4 points, Komodo is only 1 point behind Houdini in second place. The 3 engines at the bottom of the table all lost one game in RR5 and kept their relative positions. Ethereal is now a point ahead of Andscacs with one win. Fire had a weak RR with 3 losses, including one to Ethereal. It lost touch with the top 3 and is only 0.5 points ahead of Ethereal.


A few interesting games

Ethereal - Fire: Ethereal had an eval advantage in a closed position, its eval was close to 1 after exchanging queens. Then Ethereal sacrificed a bishop to open the king side, and its eval jumped over 1.5. After a series of exchanges only R vs RB remained, Ethereal 3 pawns up. In a long endgame Ethereal advanced pawns on the king side, and Fire had to give up its bishop to stop them. This left Ethereal two pawns up in a won rook ending.

Stockfish - Komodo: Stockfish had an eval over 1 and was up a pawn. Komodo reduced to a RN vs RB position and held the draw.

Stockfish - Fire: See featured game below. First loss for Fire against Stockfish in the division.

Stockfish - Ethereal: Stockfish's eval peaked under 1, Ethereal held the draw. See my live blog of the game.

Komodo - Andscacs: The black queen moved forward and Komodo attacked it all over the board. Andscacs' queen side rook was trapped in the corner and evals increased quickly. When Andscacs exchanged queens Komodo was a pawn up and its rooks were very active. Andscacs gave a bishop to free its rook, the game was soon adjudicated.

Houdini - Fire: Houdini's eval started to increase after a long shuffle. Houdini had a strong bishop pair looking directly at the black king in the corner, and open files for its major pieces. Fire tried to hold, its king had very little pawn support and eventually its defense collapsed. At the end of a series of exchanges Houdini was a piece up in a won BB vs B ending. First loss for Fire against Houdini in the division.

Stockfish - Ginkgo: Evals were close to 0 until move 30. Ginkgo underestimated the danger to its king, Stockfish's eval jumped over 2 when it opened the king side (with g4 as usual). Ginkgo was down a piece within a few moves, the game ended in a RN vs R ending.


Komodo - Chiron: Chiron kept its king in the center and pushed pawns on the king side. Komodo's eval constantly increased as it pressed the weak points in Chiron's pawn line. Komodo captured a pawn and created a queen side passer. The white knight was very strong in a closed position and Chiron traded a rook for it. The game ended in a RRB vs RBB position with Komodo's passer advancing.


Featured game: Stockfish - Fire
Premier division, round 31
Link to game on TCEC

Stockfish had an eval advantage that stayed below 1 for the first 30 moves. Stockfish had a pawn majority on the queen side and a bishop pair. The white king was a little exposed but it seemed safe enough since Fire concentrated its pieces on the queen side.




Evals jumped over 2 after the queen side opened up, Stockfish created a connected pair of passers on the queen side that looked dangerous. Fire had a passer in the center, it still thought it was relatively safe with an eval just over 1.



The engines exchanged pieces until only RB vs RN remained. The white passers on the queen side became stronger while the black passer on the e file shifted to the f file in the exchange and was no longer a passer.


Fire was forced to give its knight to take out one of the passers and the resulting RB vs R endgame was a win for Stockfish.

Season 13 live blogging, Friday Sep 21st

Today we follow the Stockfish - Ethereal game in round 33. There were only 2 decisive games so far in RR5 out of 17 played. Can Stockfish break the sequence of draws? Can Ethereal hold? I'm not considering the option that Ethereal can win, too farfetched. Stockfish and Ethereal have played 4 games so far in the division, Stockfish won twice with white and once with black, only one draw so far.

move 12: We are in the Sicilian section of Cato's openings. The 8-move book has been played in recent games of high level. Stockfish's eval at the opening is less than 0.5, relatively drawish. So far the engines are following the most played line, Stockfish's eval is starting to increase, Ethereal is still confident it can hold.

move 16: Stockfish did not expect Ethereal's move 13, its eval dropped in response, then jumped back up in the next move. Ethereal's move 15 was again unexpected, this time Stockfish's eval jumped over 0.8. The black king side loks a little weak.

move 20: Ethereal's eval dropped to 0 for a moment, then came back. Ethereal now has a passer in the center, it is not going anywhere soon though. The center opened up a little, the black DS bishop looks bad now. Stockfish's eval jumped to around 1 on move 20, Ethereal's eval also jumped over 0.5, the evals are trending higher.

move 25: Both are expecting exchanges soon. Stockfish surprised Ethereal (and everyone else) with Kg1, Ethereal's eval jumped. Then Stockfish made its signature move g4, this time eval dropping, very unstable in this game so far. Stockfish is a pawn up after exchanging a pair of bishops and a pair of knights, evals starting to come down.

move 29: Evals dropping to 0, it seems Ethereal is holding after all. The engines are delaying the exchanges, both PVs look similar and drawish. This is going to be a draw, I'll come back later to verify.

move 58: As expected the game ended in a draw, though it took 30 more moves for the draw rule to kick in.

Season 13 premier division after RR4

Crosstable after RR4


Stockfish maintained its 3.5 point lead at the top of the table. Houdini is in 2nd, extending its lead over Komodo to 1.5 points after beating it for the second time in the division. Chiron won its first game, it is still in the relegation zone together with Ginkgo. Andscacs and Ethereal are a point ahead, Fire is 2.5 points clear of Ethereal after Ethereal lost 3 games in RR4.



A few interesting games

Houdini - Chiron: Houdini's eval gradually increased after the opening. Houdini captured a pawn and created an advanced passer in the center. Chiron had to block the passer, defened its pieces and protect its king against a potential attack on the long diagonal. Chiron's defense collapsed after Houdini opened a file on the king side. Houdini reduced to a QRB vs QRN position and finished with a bishop sacrifice, leading to a won endgame.

Stockfish - Houdini: Stockfish was a rook for bishop up in a closed RN vs BN position, Houdini kept the pawn line strong and held the draw.

Ginkgo - Ethereal: For 50 moves evals were close to 0, then they suddenly jumped over 1. The engines exchanged most pieces and only RB vs RB remained and Ginkgo advanced a passer to the 7th rank. Ethereal was a pawn up but had to prevent Ginkgo from promoting the pawn, both engines couldn't improve and the game ended in a draw.

Houdini - Komodo: See featured game below. This was the second win for Houdini against Komodo in the division.

Houdini - Ginkgo: Houdini gave a rook for a bishop but had an advanced passer in the center. Ginkgo realized it was in trouble too late, its king was exposed and it had to block the passer. Ginkgo's defense collapsed and the game was adjudicated before Houdini won more material.


Komodo - Fire: Komodo had a space advantage and eval over 1, Fire seemed to be holding. The engines exchanged pieces until only N vs B remained, then Fire blundered and Komodo's eval jumped over 3. The winning sequence was not trivial and very long, probably based on the fact that the black bishop had no targets. Fire saw it was lost and the game ended without demonstrating exactly how Komodo can win.

Stockfish - Andscacs: There were many early exchanges and only RR vs RN remained on move 25. Andscacs was a pawn up and it had a pawn majority on the queen side, Stockfish had a pawn majority on the king side. Eventually Stockfish forced a rook exchange to stop a king side passer and the game reached a tablebase R vs N win for white. A double win for Stockfish in this opening

Chiron - Ethereal: Ethereal gave a pawn and tried to develop a king side attack, but nothing came out of it. The engines shuffled essentially until move 82 when Ethereal captured a pawn and gave a rook for a bishop. Evals jumped to around 2, Chiron hid its king behind a black pawn and started advancing its central passers. There was another long shuffle, then the engines reduced to a QR vs QB position and evals continued to increase. 30 moves later both engines were sure of Chiron's win, PVs showed different possible lines, both quite long. This was the first win for Chiron in the division.

Ethereal - Stockfish: Stockfish took over the game early, it attacked the king side through the half open g file. Ethereal's pieces were tied down to defend the king side and Stockfish switched to the queen side. It won a pawn and reduced to a RRB vs RRB position. Stockfish had an advanced passer in the center, the game was adjudicated before Ethereal lost material. Stockfish won both games in this opening.

Fire - Ginkgo: There were many early exchanges, only QBB vs QNN remained on move 30. Evals increased gradually, Fire exchanged a bishop for a knight and then managed to move its queen behind Ginkgo's pawns. The black king was exposed to attacks and Fire used this to reduce to a won queen ending.

Komodo - Ethereal: Komodo had space advantage on the king side, evals were close to 1 though it was a pawn down. The engines essentially shuffled until move 98, then finally Komodo started its king side attack, perhaps following a blunder by Ethereal. Komodo went up a rook for a bishop and opened the king side, then drove the black king to the center. Again the game ended long before the win was explicit.

Stockfish - Chiron: The engines castled in opposite directions, Stockfish pushed a pawn on the king side and weakened Chiron's king position. Evals increased quickly, the game reached a QN vs QB position where the black king was weak in the corner and the bishop had no pawn targets and couldn't support the black pawns. The game was quickly adjudicated. Stockfish won both sides of this opening.

Andscacs - Fire: Evals turned negative as Fire prepared a queen side attack in a closed position. However, when Fire opened the queen side evals dropped from 2 to 0. The game ended in a perpetual check.

Featured game: Houdini - Komodo
Premier division, round 24
Link to game on TCEC

The game started with evals close to 0. On move 15 Komodo allowed Houdini to block the center with a d5 pawn. Evals increased gradually as Houdini pushed pawns on the king side and had a space advantage. Komodo's pieces had less and less room to move.


Komodo tried to counter on the queen side and opened a file. Houdini blocked the file with an outpost knight on c6. Houdini continued to push its king side pawns, and when the pawn line reached g6 the black LS bishop was trapped.


Houdini concentrated its pieces on the queen side while threatening to open the king side with its pawns. Komodo had to keep an eye on both sides and its pieces were overextended. Eventually it allowed Houdini to advance a passer in the center, then gave a piece to stop it.


Houdini was up a piece and Komodo's king was trapped in the corner. This was enough for a win though the game ended before the win was evident.

Season 13 premier division after RR3

Crosstable after RR3

Stockfish is firmly in the lead after scoring 6/7 in RR3, including a second win against Komodo. Houdini drew all its games in RR3 but is still second, Komodo with 4/7 closed the gap to only 0.5 points. Ethereal lost once in RR3 and is now a point behind Fire in the race for 4th place. Chiron and Ginkgo close the table, Andscacs is a point clear of the relegation zone.


A few interesting games

Stockfish - Komodo: Komodo sacrificed a pawn on the queen side and attacked the white king side. The game reached a NN vs R imbalance, and Stockfish's eval started to increase. It advanced a queen side passer to the 6th rank. Komodo avoided exchanging queens for a while, when Stockfish forced the exchange only RBN vs RR remained and the game was adjudicated. A second win for Stockfish against Komodo in the division.

Ginkgo - Komodo: Ginkgo traded its queen for two rooks and the game reached a RRB vs QN position. Evals turned negative and gradually increased as Komodo outplayed Ginkgo. Komodo captured all the white pawns and was 3 pawns up when the game was adjudicated.

Houdini - Stockfish: Houdini was up a rook for a knight with an eval advantage, Stockfish reduced to a RR vs RN position and held the draw.

Andscacs - Stockfish: Evals turned negative over 1, Stockfish captured two pawns and created a queen side passer. Andscacs equalized material while evals continued to increase, after several exchanges only RB vs RN were left. Stockfish was two pawns up again and Andscacs' advanced passer was not strong enough. The game was adjudicated with Stockfish 4 pawns up.

Stockfish - Ethereal: The game reached a QRR vs QRR position with evals at 0. Evals started to increase on move 50, Stockfish calculated better than Ethereal. Stockfish opened the queen side and created a queen side passer. The combination of an advancing passer and threats on the exposed black king were enough for Stockfish to win. The game was over before Ethereal lost material.

Chiron - Stockfish: See featured game below.

Stockfish - Ginkgo: Evals were close to 0 for 35 moves in a closed position. Ginkgo's king was in the center uncastled, Stockfish gave a pawn and exchanged pieces, its eval jumped over 2.5. Then Stockfish created a king side passer in a QNN vs QBN position. After queens were exchanged Ginkgo was forced to lose a piece for the passer, leading to a won NN vs N endgame.

Komodo - Chiron: Komodo had an eval advantage of about 1 in a closed position. Chiron kept the evals under control for more than 40 moves. Komodo gave a pawn in a QRR vs QRR position and opened files, then Chiron blundered on move 46 and Komodo's eval jumped over 3. Komodo took over the 7th rank, exposing the black king to mate threats. It took a while for Chiron to realise it was losing.

Featured game: Chiron - Stockfish
Premier division, round 20
Link to game on TCEC

The engines castled in opposite directions, Stockfish pushed a pawn on the queen side and weakened the white king's defense. Then Stockfish sacrificed a pawn and a bishop and exposed the white king completely. Evals were negative though Chiron was a piece up.


King safety was a major concern for Chiron while Stockfish's king was safe in its corner. Stockfish drove the white king to the 7th rank and placed all its major pieces on the back rank. Analysis by Stockfish thought Chiron could still hold, until Chiron's 45th move.


Stockfish's eval jumped over 5, and Chiron's eval followed immediately. Stockfish pinned the white knight and together with mating threats and an advancing passer forced Chiron to trade a queen for a rook.


In the RRN vs QR position Chiron needed all its pieces to defend its king and Stockfish had time to capture the remaining white pawns on the king side before the game was adjudicated.

Season 13 premier division after RR2

Crosstable after RR2


The reverse games have been played and the first double RR is over. Stockfish is in the lead with a +6 score. Houdini had 4 wins in RR2 including one against Komodo, it is in second place. Ginkgo and Chiron close the table with a -4 score, Andscacs is only 0.5 a point ahead in 6th place. Fire in 4th is 0.5 points ahead of Ethereal, each has one win in their head to head games.

A few interesting games

Fire - Ethereal: Fire had a space advantage with increasing evals. Fire created a queen side passer, and though its king was exposed it attacked on the king side. After exchanging most pieces the game reached a QB vs QN position. Fire grabbed two pawns and reduced to a winning endgame. Interesting to note that Ethereal saw it was losing a long time before Fire did. A biased opening with two white wins.


Houdini - Chiron: The engines castled in opposite directions. Houdini had a space advantage, after the king side pawns stabilized it focused on the queen side. Chiron did not have enough defenders and it lost a pawn. Houdini kept pressing, it won a second pawn, and the game was adjudicated in a Q vs RB imbalance. Houdini's first win in the division.

Komodo - Stockfish: Komodo had an eval around 1 for more than 50 moves, with a rook for knight advantage. Stockfish traded down to a RR vs RB position and held the draw.

Komodo - Ginkgo: The center was blocked and the engines castled in opposite directions.  The king side had an open file that Ginkgo guarded with its rooks. Komodo's eval jumped and it exchanged a pair of rooks and created a king side passer. Then it captured a pawn on the queen side and penetrated with its queen. Ginkgo's defense collapsed and the game was adjudicated. Komodo had a double win in this opening.

Ethereal - Andscacs: The engines were essentially shufflling for a long time. Evals started to climb after Ethereal opened up the position. The game reached a RBB vs RBN position with Ethereal a pawn up. Ethereal went after the black pawns and the game was adjudicated when it was 3 pawns up. Another biased opening with two white wins.

Houdini - Komodo: See featured game below.

Houdini - Ginkgo: Houdini pushed pawns on the king side, and when the time was right it attacked the pawns defending the black king. Evals increased quickly, Houdini won a rook for a bishop and the game was adjudicated in a QRR vs QRB position. Two back to back wins for Houdini.

Stockfish - Andscacs: Andscacs gave a knight for 3 pawns, it forced Stockfish's king to walk to the king side uncastled.  The game reached a RRB vs RR position with increasing evals. Stockfish outplayed Andscacs in the endgame. Its rooks attacked the black pawns and king while it kept one pawn safe, then reduced to a winning bishop ending. A double win for Stockfish in the opening.

Houdini - Andscacs: Houdini created a queen side passer, and although Andscacs fought hard to keep it from advancing ultimately Houdini used it to win the game. The game was adjudicated in a QRB vs QRB position with the passer on the 6th rank.

Komodo - Ethereal: The game reached a QRR vs QRB position with Ethereal two pawns up and evals around 1. Ethereal's pieces were passive and its bishop almost trapped behind the pawns. Komodo weakened the black king side and captured a pawn, the game was adjudicate before Ethereal lost more material.

Stockfish - Chiron: Stockfish had an eval of about 1, Chiron held the position for over 50 moves. The engines opened files on both sides, Stockfish walked its king to the queen side and then patiently applied pressure on Chiron. The game reached a QRN vs QRN position and Stockfish captured a pawn. When it captured a second pawn the game was adjudicated.

Ginkgo - Stockfish: The game reached a R vs BN imbalance with Ginkgo two pawns up. Evals were close to 0 until move 40, then started to increase in favor of Stockfish. There was a long shuffle and then Ginkgo gave a pawn and opened the king side with pawn moves. Despite a pair of connected passers in the center for white, Stockfish thought it was winning. It reduced to a RR vs RBN position and advanced a passer to the 2nd rank. Ginkgo had to give a rook for a knight to get rid of the passer, leading to a won RB vs R endgame for Stockfish.

Featured game: Houdini - Komodo
Premier division, round 10
Link to game on TCEC

Komodo gave a bishop for 3 pawns, creating two connected passers in the center. After exchanging queens Houdini had an eval advantage under 1 with a bishop pair, though the black pawns looked intimidating.

Houdini blocked the passers with its pieces, with evals increasing. After the engines stabilized the king side pawns evals were over 1.5, though it seemed that Komodo built a strong pawn line across the board.

Houdini doubled rooks on the e file and then broke through the center giving a rook for a knight. In the RBB vs RR position Houdini's bishops were very strong, Komodo's king was trapped in the corner.

Within a few moves the black king was in a mating net, Komodo was forced to lose material and the game was adjudicated on move 36. Komodo's position collapsed very quickly, quite unexpected for an engine of this strength. 

Season 13 premier division after RR1

Crosstable after RR1



Stockfish is leading the table with a +3 score and no loss, including a win against Komodo. Komodo is the only other engine with a positive score of +1. Houdini is the only other engine with no loss, it drew all the games in the RR.
Chiron is last with a score of -2, there is a good chance it will be relegated back to division 1. Ethereal has a 0 score so far, two wins (one against Fire) and two losses. It is quite possible it will survive this division.
Some of the openings were biased and it should be interesting to see the results of the reverse games in the next RR.


A few interesting games

Andscacs - Ginkgo: Andscacs pressed hard in the opening game. Its eval peaked over 1.5 despite being down an exchange. Ginkgo managed to stop connected passers, one on the 7th rank, in a QB vs QR position. The game ended in a draw.

Ethereal - Fire: Ethereal came out of the opening a pawn down but with an advanced passer in the center and increasing evals. Ethereal exchanged pieces, giving a rook for a bishop as well. The game reached a BB vs RB position, Ethereal 3 pawns up. Fire traded the rook to force an opposite color bishop ending, still Ethereal found the win. Ethereal with a win in its opening game, how far can it go in the premier division?

Stockfish - Komodo: Featured game, see below. 

Ginkgo - Komodo: Komodo gave a bishop for two pawns early in the game. Ginkgo's king was exposed, Komodo did not attack and the engines shuffled for 20 moves. It seemed Ginkgo lost its patience, the position opened up and the engines exchanged queens, with evals increasing in favor of Komodo. Ginkgo's position collapsed, the game was adjudicated after Komodo won a piece and was 3 pawns up.

Fire - Chiron: Chiron moved its queen forward and Fire almost trapped it. By the time the queen found safety Fire attacked the back rank and black king with its rooks and queen. Fire won a bishop and the RN vs R ending was won for white.

Andscacs - Ethereal: Ethereal's 24th move led to a long series of exchanges and a RB vs RN position on move 36. Andscacs was two pawns up with eval over 1.5 and increasing. Ethereal tried to hold against two white passers, it managed to capture one but allowed Andscacs' rook to move forward and attack the black king. Andscacs found a way to exchange rooks and advance its king, winning the B vs N endgame.

Fire - Komodo: Fire was up a rook for a knight in a closed position. The engines shuffled for a very long time, both had very little time when Fire played several inaccuracies after move 98. The game reached a RRB vs RBN position with a pawn wall across the board. Only the black pieces could move freely, Komodo patiently maneuvered until it captured two pawns. Fire's position collapsed and the game was adjudicated.

Andscacs - Stockfish: Andscacs thought it was ahead when Stockfish's eval turned negative on move 31. The engines castled in opposite directions, Stockfish opened a file on the queen side with doubled rooks facing the white king. Andscacs traded Q for RB and the game reached a RBN vs QN position. It took Stockfish another 30 moves to win but there was never doubt it would.

Ethereal - Chiron: The engines castled in opposite directions, Ethereal pushed pawns on the king side towards the black king. Chiron exchanged pieces and gave a knight for pawns to open the queen side and counterattack. The game reached a RRB vs RR position, Chiron's king was trapped in the corner and the engines started to capture pawns. The game was adjudicated just before Chiron lost its last pawn.

Stockfish - Ethereal: The engines shuffled in an closed position and didn't seem to make progress. On move 45 Stockfish saw an opportunity and pushed pawns on the king side. After a long series of exchanges the game reached a RN vs R position, Stockfish converted the win without difficulty.

Komodo - Chiron: Komodo started a king side attack with a bishop sacrifice. After almost all pieces were exchanged Komodo was two pawns up in an opposite color bishop ending. Chiron held the draw but it took more than 200 moves before the evals were low enough to adjudicate. 

Featured game: Stockfish - Komodo
Premier division, round 1
Link to game on TCEC

Stockfish's eval was over 1 after book, Komodo's eval remained mostly under 0.5. Stockfish gave a pawn to open the queen side. The position was unstable, with Komodo threatening a fork with one knight, Stockfish threatening to take the other knight, the b4 pawn pinned and rooks facing each other on the d file.

There was a series of exchanges that resolved the tension. Stockfish was ahead by a knight for 2 pawns and Komodo had connected passers on the queen side. Evals increased very slowly, Stockfish's eval was close to 2 while Komodo's was still under 1. There was a long PV agreement and it wasn't clear whether Stockfish could convert.

The engines followed the PV line and the game reached a QBN vs QB position on move 33. The pieces moved around and evals did not change a lot, on move 44 Stockfish exchanged queens.


Evals were almost constant for a very long time, and the endgame was very slow. Stockfish's bishop made sure the queen side pawns did not advance. In the end Stockfish moved its king forward and this broke Komodo's defense. Can Stockfish hold the reverse game?

Season 13 division 1 final results

Final crosstable


Ethereal and Chiron promote to the premier division, Booot and ChessBrain are relegated to division 2.

Promotion of Ethereal and Chiron was never in question, they both dominated the division from the start. Fizbo lost touch with the leaders in the second half of the division, it lost three games, including a loss to Ethereal and to Chiron.

The relegation race was very close with 5 candidate engines. ChessBrain dropped to last place after a score of -5 in the second half of the division. Jonny with a score of +1 in the second half managed to climb out of the last place. Booot scored -1 and its only win of the division, it almost survived relegation. Its early crashes were its downfall, both because of the tiebreak and because of the lost points.

The premier division is about to start with Stockfish, Komodo, Houdini, Fire, Andscacs, Ginkgo, Ethereal and Chiron playing. This is the main event of the season where we get to see the really top chess engines competing, with long games and the highest level of chess. Stockfish is the clear favorite, the winner of the last two seasons. Houdini and Komodo are expected to compete for a place in the superfinal. Recall that last season Komodo won the premier league ahead of Stockfish, with Houdini only one point behind. It is unknown how well the other engines will play. Fire has been a constant 4th in the last seasons, Ethereal may also fight for 4th according to its author Andrew Grant. It is incredible that Ethereal started season 13 in division 3 and won three division in a row.

Good luck to all! 

A few interesting games

Chiron - Fritz: Fritz created a queen side passer early in the game. At first it appeared the black queen was in trouble, but it got away and Fritz connected its passer on the 3rd rank with a bishop. The game reached a RBB vs RBB position and evals gradually increased in favor of Fritz. The engines exchanged pieces and pawns, Chiron could not get rid of the black passer. In the end only bishops remained and the passer was good for a win for Fritz. A surprise loss for Chiron.

Fritz - Booot: Booot chose a RN vs Q imbalance early in the game, this turned out to be a bad idea. The black king was exposed, Chiron took over the 7th rank and together with a strong bishop pair threatened mate. The game was adjudicated before Booot lost its queen. Two Fritz wins in a row, it moves away from the relegation zone.

Jonny - Chiron: Jonny took a poisoned pawn with its queen early in the game. This quickly led to a R vs BN imbalance and negative evals around 3. It took Chiron close to 30 moves to get the win in a RN vs R endgame.

Ethereal - Fizbo: Ethereal created a central passer early in the game. A strong king side attack gave Ethereal a R vs B exchange advantage and evals over 2.5. Fizbo's compensation was the exposed white king, for a while Fizbo's eval came down below 1 while it made checks. Evals came back up and continued to increase when the white pieces sheltered the king and Ethereal had the initiative again.The game reached a RNB vs RB position and was adjudicated before the endgame was played out. This was the first loss for Fizbo in the division.

Chiron - ChessBrain: Chiron was a pawn up early in the game. The engines exchanged most of the pieces and only RN vs RB remained on move 23. Chiron created a queen side passer and reduced to a winning rook ending.

Fizbo - Fritz: Fizbo trapped a black rook and went up R vs N exchange. Fritz tried to counter with a queen side passer, Fizbo made sure it won't advance. Fizbo created a passer in the center and then exchanged down to a RB vs BB position. The white passer was worth a piece and it gave Fizbo the win.

Jonny - Laser: See my live blog of the game. Jonny had a R vs B exchange advantage and the game reached a RRB vs RBB position on move 30. Jonny controlled the 7th rank and after exchanging a pair of rooks it managed to get a winning endgame. Jonny's win complicated the bottom of the table.

Ethereal - Chiron: See featured game below. Ethereal wins and evens the head to head score against Chiron.

Laser - ChessBrain: Laser had an eval over 2 when the position opened up in a RRB vs RRN position. The game reached a rook ending with Laser a pawn up. ChessBrain did not have tablebase access and didn't realize it was lost until the game reached a tablebase adjudication.

ChessBrain - Fritz: ChessBrain went up a pawn early in the game. After some shuffling the engines exchanged pieces until only B vs N remained, Fritz had to block the white passer on the queen side and ChessBrain found a zugzwang win.

Ethereal - Laser: Laser got into trouble very early. Ethereal didn't castle, instead it launched a deadly king side attack. Evals shot up quickly, Laser exchanged most pieces and lost only a little material. The game reached a R vs B position, and an easy win for Ethereal.

Fritz - Ethereal: Evals were stable and close to 0 until Fritz decided to sacrifice a knight. It got 3 pawns in return and two passers, but evals became negative and increased slowly. Ethereal exchanged pieces until only BNN vs BB remained, then it captured the white passers with evals over 2. For a while it seemed Fritz might be able to hold a draw with its bishop pair, but then it blundered the game away.

Jonny - ChessBrain: Jonny won a pawn, then after some preparation exchanged down to a RB vs RB position. The endgame was very slow, Jonny captured a second pawn and had a king side passer. ChessBrain's lack of tablebase support was evident again, Jonny reduced to a winning 6-man position and ChessBrain thought it still had a chance.

After RR3 the standings are Ethereal +9, Chiron +5, Fizbo +1, Fritz -2, Jonny -3, ChessBrain -3, Laser -3, Booot -4. There are 5 engines fighting against relegation, Booot's crashes against ChessBrain and Fritz were very unfortunate.

Fizbo - ChessBrain: ChessBrain chose to open the king side, putting its king at risk. Fizbo was up a pawn with a bishop pair facing ChessBrain's knight pair, ChessBrain had an advanced passer in the center as compensation. The game reached a RBB vs RNN position, the bishops were very strong and the exposed black king was an easy target. ChessBrain lost a piece for pawns, Fizbo won the endgame.

Fritz - Chiron: Fritz had a small eval advantage for the first 50 moves, when the position opened evals became slightly negative but still close to 0. The game seemed to be heading for a draw, after a long shuffle Chiron took the initiative on move 80. It took a while but after most pieces were exchanged the game reached a RB vs Q ending. Chiron captured the remaining white pawns and reduced to a winning 6-man position.

Ethereal - ChessBrain: Ethereal gave a knight for 3 pawns. The game reached a RB vs RBN position and for a while it seemed ChessBrain can hold. On move 64 ChessBrain blundered and Ethereal's eval started to jump. It took Ethereal 20 more moves to reduce to a winning rook ending.

Only 4 rounds to go, the bottom of the table is Fritz -3, Jonny -3, Laser -3, Booot -4, ChessBrain -5. ChessBrain lost twice, but its remaining games are only against the other bottom 5 engines. All other contestants have at least one game to play against the top 3, Booot has to face all 3. Nothing is decided yet.

Fritz - Fizbo: Fritz was a pawn up early in the game, with an eval advantage that increased over 1. Fizbo gave a second pawn, opened the king side and threatened the white king. Fritz exchanged pieces and the game reached a QBN vs QR position. Evals slowly came down, then shot up over 2 after an unexpected Fizbo blunder. Fritz drove the black king out of the corner and captured a pawn, evals slowly increased until the game was adjudicated. An unexpected win for Fritz. 

Booot - ChessBrain: The engines castled in opposite directions, ChessBrain gave a pawn to open the queen side and tried to attack the white king. After a series of exchanges the game reached a RN vs Q imbalance, Booot 2 pawns up and evals over 1. ChessBrain's attack on the white king was not strong enough, a white passer forced ChessBrain to lose a piece. Booot's material advantage was enough for a win. This is Booot's first win of the division.

Fizbo - Chiron: The game started in a closed position. Chiron opened the king side and had much more space. It increased the pressure with the queen and a passer on the queen side and rooks on the king side. The game was adjudicated before Fizbo lost material. Two straight losses for Fizbo.

Now only 2 rounds to go, the bottom of the table is Fritz -2, Jonny -3, Laser -3, Booot -3, ChessBrain -6. ChessBrain is very close to being relegated back to division 2, Fritz and Booot improved their chances to survive.

Booot - Chiron: Booot had a small eval advantage from the opening, though Chiron had a queen side passer. Chiron took over after Booot gave a bishop for three pawns including the black passer. The game reached a R vs RB position, Chiron gradually captured and exchanged pawns. The game ended in a tablebase win for black. This loss means that Booot must win its last game to have a chance of surviving.

Fizbo - Booot: Fizbo had the advantage in a RRB vs RRB position, the game ended in a tablebase draw. Booot cannot survive, it will lose any tiebreak because of crashes.

Chiron - Laser: Chiron created a passer on the queen side. As the engines exchanged pieces the evals increased gradually, Chiron also had a bishop pair advantage. Eventually Laser lost a piece to get rid of the passer, the game reached a QBB vs QB position. It took Chiron a while, and perhaps Laser blundered but in the end Chiron found the win.

Ethereal - Fritz: Ethereal was a pawn down when suddenly its eval jumped over 3. Apparently Fritz ignored the danger to its king and was late in developing its queen side pieces, and it was slow to realize it was losing. Fritz gave a knight and exchanged pieces, its king was still vulnerable in a QRN vs QR position and the game was soon adjudicated.

Featured game: Ethereal - Chiron
Division 1, round 18
Link to game on TCEC

Evals were close to 0 with a small advantage to Ethereal. After the opening Ethereal had an isolated pawn in the center, Chiron moved its rook forward to apply pressure on it.



The rook immediately became a target. Ethereal could exchange it for a bishop but it made some preparations first. When the exchange was made Ethereal also had passers on the queen side. Evals were over 1 and increasing.


After exchanging queens the game reached a RBN vs BBN position. Chiron had an advanced passer but after Ethereal got rid of the black LS bishop Chiron lost control of the the queening square. 


Ethereal used attacks on the black king and pieces to advance its passer to the 7th rank and get a winning position.

Season 13 division 1 statistics

Draw rate, wins



Final draw rate was 62.5%.

Game termination

The three most common game termination causes were:
33.9% - TCEC draw rule
25% - TCEC win rule
24.1% - SyzygyTB

There were 2 crashes in the division.

Moves per game



Median= 55.3
Average= 61.1

There were only 7 games longer than 100 moves, the longest was 157 moves (Jonny - Laser, round 4, draw). 

Time per game (hours)



Median= 2:06
Average= 2:04

Openings

There were 2-move book openings in this stage chosen by Cato. Each opening was repeated 4 times in a round, and then again in the reverse games round. In total 14 2-move openings were used. The first letter of the ECO codes was distributed as follows:



If we use the opening 'family name' (using format FAMILY_NAME: VARIANT....) the top 3 are:
QGD - 16 times
Sicilian - 16 times
English - 11 times

The engines had a lot of freedom to choose the opening variant. Only 19.6% of the game pairs repeated the same ECO code twice, and 14.3% repeated the same opening variant. In 14.3% of the game pairs the ECO first letter was not repeated twice.

Reverse pairs, wins



Reverse pairs, same moves 

Pairs of reverse games diverged very quickly, 91.2% of the pairs diverged at most after 1 move. The longest repeated move sequence in a game pair was only 9 plys long.