Season 13 superfinal, games 9-20

After 20 games Stockfish leads 3-0 with 17 draws.

Stockfish is slowly accumulating wins, Komodo has not been able to convert opening advantages into wins yet. I hope to see a Komodo win soon, this will make the match more interesting.

In games 9-10 black was up a knight at the book exit, the black king was exposed and the white pieces were better placed. In game 9 both engines had a 0 zero eval from start to finish. The position opened up and reached an unusual RR vs BBN imbalance. Both kings were under threat and the game ended in a perpetual check draw. Stockfish's (negative) eval jumped to 1 at the start of game 10. At first Stockfish gave the material back, though after several exchanges it was again a bishop up. Komodo used the exposed black king to win some material back, creating a R vs BN imbalance. Stockfish had a central passer that reached the 2nd rank, after exchanging queens only RR vs RBN were left and evals started to come down. Komodo gave a rook for a bishop to remove the black passer. In the R vs RN endgame Komodo was 2 pawns up, and that was enough for a draw.

Both engines stayed behind their pawn lines with very few exchanges in game 11. The position became static on move 38 and then the engines started to shuffle. The 50 move draw was avoided twice by exchanges, the game was adjudicated on move 152. In game 12 the position opened up with a series of exchanges, and the game reached a double rook ending on move 34. Komodo had an advanced passer in the center and evals were close to 1. The passer could not advance beyond the 6th rank and evals came down to 0. The game was adjudicated when all the other pawns were gone.

Komodo was up a pawn early in game 13, Stockfish was ahead in development. Komodo gave the pawn back and its defense was solid. After a series of exchanges only RRN vs RRN remained with evals at 0, the engines agreed on a draw. In game 14 Stockfish held on to its pawn advantage and Komodo had more space. After a few exchages Stockfish built a pawn line across the board and the engines started to shuffle. The game ended in a 50 move draw.

Stockfish was up a pawn early in game 15, its eval was over 1. Komodo took over the open d file with doubled rooks and attacked the white king. After a few exchanges Komodo created a central passer and evals came down to 0. Stockfish gave a rook for a knight to get rid of the passer. The engines exchanged most of the remaining pieces and the game reached a N vs R drawn ending. In game 16 the center was blocked and Komodo had a space advantage. After opening a file on the queen side the engines exchanged all the rooks, and evals came down to 0. The engines continued to exchange pieces until reaching a tablebase draw.

In game 17 Komodo traded its bishops for knights early. Stockfish's eval jumped over 1.5 when Komodo captured a pawn on the queen side, Komodo's pawns there became connected passers but they were also the black king's shield and couldn't advance. Stockfish had strong pawns in the center, and the open position also meant more strength for the white bishop pair.


The engines shuffled for a while, evals started to increase after Stockfish opened the king side. It now had two passers, one in the center and one on the king side. Komodo started to feel the danger.


After exchanging queens Stockfish captured a pawn, another exchange led to a second pawn capture. Stockfish was up 2 pawns in a RRB vs RRN position and Komodo's defense crumbled.


Stockfish reduced to a double rook ending 3 pawns up before the game was adjudicated.

In the reverse game Stockfish kept one of its bishops and castled short while Komodo castled long. Stockfish pushed pawns on the queen side and Komodo was slow in developing a king side attack. Only QRB vs QRB remained on move 29 and evals fell to 0. Komodo attacked the white king but could only get checks, the game soon ended in a draw. Another minimatch win for Stockfish.

In games 19-20 black had holes in the pawn structure on both sides of the board and no safe option for castling, while white castled long. In game 19 Komodo pushed pawns on the queen side and castled short. The queen side opened and Stockfish was busy defending against Komodo's bishop pair. Evals came down to 0, the engines exchanged pieces until QRN vs QRR remained with Stockfish 2 pawns up. The black rooks chased Stockfish's queen and the game was adjudicated a draw. In game 20 Stockfish castled long, and evals quickly fell to 0. Stockfish attacked on the queen side and for a while evals were slightly negative, but nothing came out of it. The engines exchanged pieces until reaching a drawn QR vs QR ending.

Season 13 superfinal, games 1-8

The TCEC cup is over, Stockfish won the event after beating Houdini in the final. Perhaps more interesting was the semi-final match against Leela (Lc0). Leela beat Ethereal and Fire in the earlier rounds in very long matches. Leela seemed to play the openings and middlegames better, but it would sometimes blunder in the endgames or be surprised by a perpetual check draw by the opponent. Leela was no match to Stockfish in season 13, it will be very interesting to see it in the next season. It will surely reach the premier division, I'm not sure whether it can handle the top 3.

The Stockfish - Komodo superfinal of season 13 has started. After 8 games Stockfish leads 2-0 with 6 draws.

Komodo opened the queen side early in game 1, and after a series of exchanges only RBN vs RNN remained on move 26. Stockfish had a queen side passer which looked dangerous, with an eval over 1.


Evals remained mostly unchaged for a while. The engines exchanged a pair of knights and Komodo used its extra pawn on the king side to create a passer in the center. Stockfish's eval started to increase after it won a pawn. It then abandoned its queen side passer and sent its rook to the king side and created passers there.


Stockfish finished the game with a rook for knight sacrifice.



The black pawn on f4 could not be saved and the 3 white passers that remained were eventually unstoppable.

In the reverse game Komodo had a pawn majority on the queen side but no passer. The pieces remained on the board longer, and evals started to drop to 0 after the engines exchanged all the rooks. The game reached a BN vs BN position on move 61. The engines continued to shuffle and exchange pieces until adjudication with only pawns left. First minimatch goes to Stockfish.

In game 3 Komodo's king remained uncastled, yet it was not in danger after the engines exchanged most pieces early. Stockfish's eval started around 1 but started to come down after 25 moves. The game ended in a repetition with RBN vs RBN on the board. Game 4 also had many early exchanges, resulting in a RBN vs RBN position. This time Komodo was a pawn up and had a 3 vs 1 pawn majority on the queen side. Komodo's eval was over 1.5 while Stockfish reduced to an opposite color bishop ending. Komodo had a queen side passer but it could not push it beyond the 6th rank. Stockfish was able to hold the white king back. It took Komodo a very long time to agree to a draw after 175 moves.

Stockfish castled long in game 5, and then it pushed the queen side pawns to force back a black bishop. This left the white king very exposed, and Komodo gave a knight while its pieces controlled the center where they could threaten the white king. Komodo thought it had enough compensation for the piece, Stockfish's eval was over 1 but it had to be careful.


The white pieces were static and pinned down, but somehow the white king remained safe. Komodo captured two pawns on the king side and created a passer in the center. Stockfish exchanged a few pieces, its king was still exposed but out of danger since only Komodo's queen could attack. 


The white pieces became more active, after making sure the black passer was blocked Stockfish started to plan its attack. Komodo's king side was vulnerable and Komodo had to defend while being a piece down. Stockfish's eval was winning as it left a pawn hanging for Komodo to take.


Stockfish sacrificed a knight for the g6 pawn and pinned the rook after it took the knight. All the black pieces surrounded the king, leaving the c7 pawn unprotected. Stockfish's c pawn became an advanced passer and this was enough for a win.

In the reverse game 6 both engines castled short and the position remained closed with all pawns on the board. Komodo had a space advantage with evals over 1. Stockfish exchanged its bishops for white knights and after queens were exchanged Komodo could not find a way through the pawn wall. Komodo refused to acknowledge it was a draw, the game continued till move 197. A second minimatch win for Stockfish.

Games 7 and 8 were King's Gambit variants. There were many early exchanges in game 7 and only RB vs RN remained on move 24. Evals were low throughout the game and adjudication came quickly. Evals were low in game 8 as well. Komodo gave a knight to remove the black advancing pawns on the king side. The black king was exposed and Stockfish gave a rook for a knight to stop Komodo's attack, leading to a R vs NN imbalance. After stabilizing the queen side the engines agreed to a draw in a QR vs QNN position.

Season 13 premier division final results

Final crosstable


The premier division is over, the season 13 superfinal will be between Stockfish and Komodo. Chiron and Ginkgo are relegated to division 1.There were no changes in the crosstable in the last RR, except for Chiron and Ginkgo switching places. The race for the top was over quickly, the race at the bottom of the table was still open in the final 3 rounds but Andscacs was never in real danger. Ginkgo scored its only win in the division, Houdini lost for the second time, this time against Stockfish.

Judging from the results of the last two superfinals we may assume that Stockfish is going to win again in a very one-sided match. On the other hand, the 8 games played between Stockfish and Komodo in this division had a 3-2 result, so Komodo has the ability to win games against Stockfish and it may get lucky.

The Superfinal is scheduled to start after a new TCEC cup event. I haven't decided how closely I will follow the cup event, I may take a few weeks break from the blog.



A few interesting games

Ginkgo - Andscacs: Ginkgo had an eval advantage that increased after the start, reaching over 1.5 in a RBN vs RBN position. Ginkgo had an advanced passer that got to the 7th rank, Andscacs gave a knight to stop it. Ginkgo's eval peaked over 2.5 in BN vs B ending, but Andscacs held the draw. That was Ginkgo's last realistic chance to avoid relegation. With 6 games left it is 2 points behind Andscacs.

Fire - Ethereal: The game reached a RBN vs RBN position on move 24, Fire had an eval advantage. Fire had a pawn majority on the queen side and its king advanced to the center, Ethereal had a king side passer and its king was trapped in the king side corner. It took Fire more than 20 moves to capture the black passer, with only RB vs RN left and 4 white against 3 black pawns on the queen side. After 20 more moves Fire captured another black pawn and Ethereal's defense crumbled. The game was adjudicated with 2 white passers close to queening. After this win Fire is 2.5 points ahead of Ethereal.


Houdini - Chiron: Houdini went a pawn up early in the game. It then gave a rook for a knight, evals were over 1. The engines exchanged pieces until only RB vs RR remained, Houdini created a connected pair of passers in the center and Chiron gave a rook for a bishop in an attempt to stop them. The rook ending was a win for Houdini. Double win for Houdini in this opening.

Komodo - Stockfish: Komodo had an eval advantage from the start. After a series of exchanges most of the queen side was clear, both engines had a passer. Komodo captured a pawn and created a second passer on the queen side, after exchanging queens it pushed the passer to the 7th rank. Stockfish reduced to a RB vs RB position and removed the dangerous pawn, while Komodo went two pawns up, enough for a win. The opening was biased, two white wins. Komodo is still 2 points ahead of Houdini in 2nd place.

Komodo - Ginkgo: Komodo gave a pawn early, Ginkgo's king was exposed on the king side and Komodo had an eval close to 1. Ginkgo's pawn structure had a weak e6 square, it took Komodo 15 moves to get a well guarded knight there. Ginkgo couldn't get rid of it and Komodo won a knight. The game was adjudicated in a BNN vs BN position. A double win for Komodo in this opening.

Stockfish - Houdini: See featured game below. After this loss Komodo is 3 points ahead of Houdini with 5 games remaining. Stockfish is 6 points ahead of Houdini, it has qualified to the superfinal.

Ethereal - Andscacs: Ethereal had an eval advantage, there were many early exchanges and by move 30 Ethereal was a pawn up and all the queen side pawns were gone. Evals did not move for a while in a RBN vs RBN position, but after a long shuffle Ethereal found a way to improve. Andscacs took longer to see it was losing, it became evident when Ethereal won a knight using pins and attacks on the black king. The game was adjudicated after there were no black pawns left. Andscacs is 1.5 points ahead of Chiron, still not safe.

Ginkgo - Ethereal: Ginkgo went a pawn up while its king side was a little vulnerable. Ginkgo had passers in the center and Ethereal pushed pawns on the king side. The game reached a QRR vs QRR position, evals increasing all the time. Ethereal tried to block a white passer, Ginkgo managed to get it to the 7th rank. Ethereal's defense collapsed and it started to lose pawns, the game was adjudicated with Ginkgo 3 pawns up. An unexpected win for Ginkgo, its first in the division.

Andscacs - Chiron: Andscacs was up a pawn and the game reduced to a RB vs RN position on move 23. Chiron allowed Andscacs to exchange rooks and evals jumped over 2. Chiron could not stop the white king from advancing, the game was adjudicated before Andscacs captured more pawns. Ginkgo and Chiron, switch places, Ginkgo is 7th 0.5 point ahead of Chiron.

Stockfish - Andscacs:Stockfish had an eval advantage that constantly increased. Andscacs had very little space to move, Stockfish waited for the right moment to attack and win a bishop. The game was adjudicated a few moves later.

There are 3 games left for each engine. Komodo is 3 points ahead of Houdini, it will be the second qualifier for the superfinal. At the bottom the scores are Andscacs -10, Ginkgo -13, Chiron -14. The relegation race is still open. 

Ginkgo - Chiron: Ginkgo had an eval advantage, temporarily it was a pawn up but the game ended in a drawn queen ending. Ginkgo and Chiron's remaining games are against much stronger engines, this was probably their last chance of a win.

Houdini - Andscacs: Houdini's eval was around 1 for a while, then started to increase as Houdini pushed pawns across the board. Andscacs attacked the king side briefly, then Houdini sacrificed a knight and created two passers on the queen side. Andscacs gave a rook to stop a passer, in a RBN vs BNN position Houdini's rook attacked the black pawns. The game was adjudicated in a N vs B ending with Houdini 2 pawns up. Despite the loss Andscacs is a point ahead of Ginkgo with one game left, Ginkgo is playing Stockfish...

Komodo - Ethereal: Komodo's eval increased to 1, Ethereal had a trapped knight on the queen side while the engines struggled to control the center. Evals jumped over 2 after Ethereal opened a way out for its knight, while Komodo created a central passer. After seeral exchanges only QR vs QBN remained, the combination of the passer and threats against the black king allowed Komodo to reduce to a winning king and pawns ending.

Featured game: Stockfish - Houdini
Premier division, round 51
Link to game on TCEC

Stockfish had an eval of around 1 from the start, the engines castled in opposite directions. There were several early exchanges that opened the center. Houdini gave a pawn and pushed pawns on the queen side. Stockfish won a second pawn, clearing most of the black pawns on the queen side. However,  its king faced the black major pieces.



To get out of trouble Stockfish gave a rook for a bishop and the game reached a QRB vs QRR position on move 26. Stockfish was two pawns up and it had 3 connected passers on the queen side, its eval continued to increase quickly. After exchanging a pair of rooks the immediate threat to the white king was removed.


Stockfish started to push its queen side passers. Houdini's king was in the corner and under threat on the dark squares, with the white bishop on the long diagonal. By the time Houdini moved its king away from danger Stockfish formed a strong pawn chain on the queen side.


Houdini could not stop the white pawns without losing material, the game was adjudicated a few moves later.

Season 13 premier division statistics

Draw rate, wins

 
Final draw rate was 67.4%.

Game termination

The three most common game termination causes were:
35.7% - TCEC draw rule
32.1% - TCEC win rule
17% - SyzygyTB

There were no crashes in the division.

Moves per game

 
Median= 58.3
Average= 67.5

There were 25 games longer than 100 moves, 7 games longer than 150 moves. The longest game was 217 moves (Komodo - Chiron, round 7, draw). 

Time per game (hours)

 
Median= 2:54
Average= 2:54

Openings

There were 8-move book openings in this stage chosen by Cato. 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:
Sicilian - 42 times
French - 18 times
King's Indian - 13 times

The engines had almost no freedom to choose the opening variant. In fact all but one of the game pairs repeated the same ECO code and opening variant twice. The first game was a A69 Benoni and the reverse game was a E77 King's Indian.

Reverse pairs, wins


Reverse pairs, same moves 


Pairs of reverse games diverged very quickly, 83% of the pairs diverged at most after 1 move. The longest repeated move sequence in a game pair was 16 plys long (Chiron - Ginkgo, rounds 19 and 26, Philidor's defense, two draws). 

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.