Season 16 superfinal games 1-10

After 10 games the score is 1-1 with 8 draws. In the premier division Stockfish beat AllieStein 3-0. However AllieStein updated its net and it appears to be better in the superfinal. Hopefully Stockfish will be stable in the superfinal, I wouldn't want crashes to affect the outcome of the match.

Games 1-2 were played without a book start sequence. Game 1 was a French opening, Steinitz variation. Queens were off early and both engines did not castle. AllieStein went a pawn up and the engines started to shuffle in a closed position. The 50-move draw was avoided twice before the engines lowered their evals for adjudication by the draw rule on move 137. Game 2 was a Semi-Slav defense. The engines opened files on the queen side and exchanged most pieces, only QB vs QN were left on move 24. After exchanging queens AllieStein's eval turned negative, the endgame was stopped by a 50-move draw.

Games 3-4 were a King's Indian defense. In game 3 AllieStein broke the diagonal pawn lines and allowed Stockfish to create a passer in the center. The engines mostly shuffled from move 19, evals increased as AllieStein had more space and Stockfish's king was vulnerable.



AllieStein used the open long diagonal for a constant mate threat, then pushed the a pawn forward to the 6th rank. The black pieces were forced to defend passively. 



AllieStein attacked on the king side, Stockfish gave a rook for a bishop and exchanged pieces until only RR vs RN remained.



The material advantage and passer on the 7th rank were enough for a win. First blood in the superfinal for AllieStein.

In game 4 Stockfish kept the diagonal pawn lines and this allowed AllieStein to create pressure on the king side, its eval turned negative. AllieStein opened the king side, Stockfish countered on the queen side and gave a rook for a bishop. after many exchanges the game reached a QBN vs QR position, the king side attack was mostly over and the white king escaped to the center. The game ended in a perpetual check draw. AllieStein wins the first game pair.

Games 5-6 started with a 19-ply book sequence in the Sicilian, Paulsen variation. In game 5
the engines castled in opposite directions, AllileStein pushed pawns on the king side and thought it had an advantage. Stockfish surprised with a rook sacrifice that opened the queen side, forcing a quick perpetual check draw.

Game 6 started similarly, Stockfish pushed a pawn to h6 and caused the long diagonal to open, weakening the black king. AllieStein countered on the queen side but was not able to break Stockfish's defense or to force a perpetual check draw. Stockfish moved a bishop to g7 in front of the black king, its eval increased over 2.

Stockfish opened the f file and threatened immediate mate. AllieStein's pieces were far on the other side, Stockfish traded its queen for a rook and bishop, removing the last defenders. Only RRB vs QR remained, Stockfish's eval jumped over 14.

Black had to use all its pieces to avoid mate on f8. Stockfish created a passer on the queen side and the game was adjudicated, PVs showed that after exchanging all pieces on f8 black can't stop the passer. Stockfish wins a game pair and equalizes.

Queens were off early in game 7 and Stockfish kept its king in the center. After a series of exchanges only RR vs RBN remained, most of the pawns were gone and both kings were exposed. AllieStein's eval stayed over 1.5 for a long time, it created a king side passer and managed to push it forward while Stockfish captured the remaining white pawns. AllieStein sacrificed its rooks and queened the pawn, this led to a drawn Q vs RB ending. In game 8 AlllieStein castled its king and the position remained closed. Evals came down to 0 after files were opened on both sides, the game reached a RN vs RB position and ended in a tablebase draw.

Games 9-10 were a King's Gambit Accepted variant. There were many exchanges after the start of game 9, evals came down to 0 and the game reached a rook ending on move 31. AllieStein thought it had a small advantage, the game continued for 40 moves until it lowered its eval for adjudication by the draw rule. In game 10 the pieces stayed on the board longer, both kings were uncastled in the center and queens were off early. Stockfish's eval was 0, AllieStein thought it had an advantage. The game reached a RBN vs RBN position on move 42, a N vs B ending on move 61, and ended in a tablebase draw.

Season 16 premier division final results

Final crosstable

Stockfish and AllieStein qualify for the superfinal. Stockfish survived without crashing a third time and even finished first. Leela finished third and will not defend its title, despite it being the only undefeated engine and the only engine to beat Stockfish in the division (not through a crash).

The fact that Stockfish was not disqualified means that KomodoMCTS and ScorpioNN are relegated to league 1 next season. ScorpioNN and Stoofvlees started season 16 in the qualification league, both reached the premier division but only Stoofvlees managed to stay in the division for next season.

Leela fans will be disappointed that Leela did not qualify for the superfinal. For AllieStein this will be a first superfinal appearance, in only its second TCEC season. Stockfish is still a top engine despite the NN revolution. In the premier division Stockfish beat AllieStein 3 times. In the superfinal Stockfish will fix its bug and AllieStein will have a new version, I hope to see a competitive match.

A few interesting games

The leaders' scores with 7 games left are: AllieStein +9, Stockfish +8, Leela +6. Stockfish still has 2 crashes, one of those was a gift to AllieStein. Leela is without a loss but needs wins to close the gap.

ScorpioNN - Leela: The game reached a QRR vs QRR position with most pawns on the board. After some suffling the engines exchanged queens, then ScorpioNN blundered and allowed Leela to capture two pawns and create passers on the queen side. ScorpioNN had a king side passer, both engines lost a rook to remove a passer and this left a winning rook ending for Leela. Leela won this opening from both sides.

Houdini - AllieStein: AllieStein had a pawn majority on the queen side and evals turned negative. AllieStein's eval increased quickly after the majority became a supported passer on the 3rd rank. The engines gradually exchanged pieces until only RB vs RN remained, AllieStein lost the queen side passer but was a pawn up with a central passer. AllieStein took its time and didn't push the pawns. The engines shuffled a lot, Houdini lost patience and pushed a pawn. AllieStein captured the pawn and went back to shuffling. The game was finally adjudicated on move 180. A double win for AllieStein in this opening.

ScorpioNN - Stockfish: ScorpioNN gave a rook for a knight early, the position was static and the engines started to shuffle. At move 104 Stockfish's eval jumped over 2 (negative), ScorpioNN blundered with seconds left on its clock. Within a few moves Stockfish reduced to a QB vs QR position, its eval over 13. ScorpioNN gave its queen for a rook to stop mate on the back ranks, a win for Stockfish.

Leela - Komodo: Leela gave a pawn on the queen side and evals started to increase. Komodo sacrificed a bishop for pawns and opened the king side, then gave a knight and exchanged queens. The game reached an unusual RBNN vs RN position with black 4 pawns up. Leela was very patient and Komodo's eval increased slowly. It took Leela 30 moves to capture 3 pawns, and another 30 moves for evals to be high enough for adjudication.

Stoofvlees - AllieStein: Stoofvlees had an eval advantage from the start. The engines mainly shuffled behind their pawn lines. Stoofvlees opened the center and tried to attack the black king, it forgot that its own king was exposed and AllieStein's eval suddenly jumped over 7 (negative). AllieStein's attack was lethal and Stoofvlees lost its queen to defend its king. The game was adjudicated a few moves later. Another double win for AllieStein.

Only 4 games left, the top of the table is: AllieStein +11, Stockfish +9, Leela +8. Leela is only 0.5 points behind, Stockfish and Leela drew their game, AllieStein with two more double wins is leading comfortably.

Stockfish - AllieStein: see featured game below.

Leela - Houdini: Leela opened a file on the king side and the black king ran to the center. Evals gradually increased as the engines exchanged pieces. Houdini went a pawn up and the game reached a RN vs RN position, evals were close to 2. Leela's rook was on the 7th rank and it had an advanced passer, Houdini was able to stop the passer but by then Leela was two pawns up. The game went on for 35 more moves before adjudication.

Only 2 games left, the top of the table is: AllieStein +10, Stockfish +10, Leela +9. AllieStein lost to Stockfish for the third time in the division, the race for the superfinal is wide open. Leela and AllieStein drew their game, the remaining opponents of the leaders are lower ranked engines.

Houdini - Stockfish: Houdini's queen captured two pawns on the queen side, Stockfish gave a rook for a bishop and the game became wild. Both kings were exposed and uncastled, Stockfish lost another knight but Houdini had a trapped rook and its king was in danger. Houdini gave the material back and the game reached a QRB vs QRB position, Houdini was two pawns up but Stockfish's king was safe and this was a huge advantage. It took Stockfish 30 moves to capture 4 pawns while chasing the white king, enough for a win. Stockfish won both games in this opening.

Final scores: Stockfish +11, AllieStein +10, Leela +9. Both Leela and AllieStein drew their last two games, Stockfish survived to the end and even finished first despite having two crashes.

Featured game: Stockfish - AllieStein
Premier division, game 158
Link to game on TCEC

Stockfish had an eval advantage from the start. The engines castled in opposite directions, Stockfish pushed pawns on the king side facing the black king. AllieStein countered with pawns on the queen side and then sacrificed a knight to expose the white king. Stockfish's eval increased over 1.5.

Stockfish opened the king side and pushed a pawn to the 7th rank. AllieStein opened a file on the queen side and threatened mate, however Stockfish was not intimidated and its eval jumped over 9.

Stockfish gave a knight to defend its king, but its king side attack put AllieStein's king in real danger. AllieStein lost material so its king could escape, and Stockfish queened its passer. 

Stockfish had two queens attacking, the game ended with mate on the board a few moves later.

Season 16 premier division after RR5

Crosstable after RR5

Stockfish scored +3 in RR5 while AllieStein and Leela only scored +1. As a result AllieStein and Stockfish are leading and only 0.5 points apart, Leela is in 3rd 1 point behind Stockfish. There is only one RR left in the division and it is possible that Leela, last season's champion, will not qualify for the superfinal.

Stockfish survived another RR without a crash, though every occasion it thinks long on a move is a source of drama - is it thinking or crashing? If it survives RR6 there is a good probability it will qualify for the superfinal despite having two crashes. Both Leela and KomodoMCTS are hoping for a third crash.

A few interesting games

Leela - ScorpioNN: There were no exchanges other than a pair of bishops in the opening, the engines played behind their pawn lines. Evals started to increase after the position opened up a little on the queen side. The game reached a B vs N ending, Leela a pawn up. Leela created connected passers on the king side and that was enough for a win.

Stockfish - Stoofvlees: Stockfish outplayed Stoofvlees in a BN vs BB ending. After locking the king side Stockfish created a passer on the queen side and reduced to a N vs B position. The black bishop had to watch the passer, and the white pieces were able to create a passer on the king side to win the game.

AllieStein - Houdini: AllieStein trapped a black bishop and its eval started to increase. The engines exchanged pieces gradually, AllieStein captured the trapped bishop and the game reached a RBB vs RB position with no pawns. Both engines thought the 7-man position was a win for white and the game was adjudicated quickly, before the win was demonstrated.

AllieStein - Stoofvlees: Stoofvlees missed a mate threat tactic and lost a piece, the game reached a RRB vs RR position. The engines played on for more than 50 moves and the game ended with mate on the board.

Stockfish - Houdini: Stockfish had an eval over 1 from the start. Both kings remained in the center, Stockfish pushed pawns on the king side and one reached the 7th rank. There were many early exchanges and only RB vs RB remained, Houdini was a pawn up but its rook had to block the white pawn on g7. Houdini lost its bishop to remove the white passer and the game was adjudicated a few moves later.

Komodo - AllieStein: see featured game below.

KomodoMCTS - Stockfish: Stockfish pushed pawns on the king side and concentrated forces. Its eval jumped over 5 (negative) after it opened the h file, KomodoMCTS realized it was in trouble a move too late. The king side threat was too strong, KomodoMCTS lost a rook and then was a full queen down. The game was adjudicated quickly.

Featured game: Komodo - AllieStein
Premier division, game 136
Link to game on TCEC

AllieStein was a pawn up early, evals were close to 0 as the engines exchanged many pieces. Both engines had passers on the queen side, Komodo's passer was on the 6th rank. 


AllieStein moved its king forward and immediately regretted it, both evals jumped over 1.5. The white rooks could attack the black king, Komodo captured a pawn and pushed its passer to the 7th rank.


After exchanging a pair of rooks the game reached a RB vs RN position. The engines captured the queen side passers and Komodo captured all the black pawns and went two pawns up.


Komodo pushed the pawns forward, the game continued for another 15 moves before adjudication. An unexpected loss for AllieStein, first win for Komodo against one of the top 3 engines.

Season 16 premier division statistics

A summary statistics table of previous stages and seasons. 

Draw rate, wins


Final draw rate was 71.4%.


Game termination

The three most common game termination causes were:

33.3% - SyzygyTB
24.4% - TCEC draw rule
17.9% - 3-Fold repetition


There were 2 crashes in the stage, both by Stockfish.

Moves per game


Median= 73.5
Average= 83.5

The games are longer when NN engines are involved, due to different scoring methods that delay the application of the win and draw rules. There were 39 games longer than 100 moves, the longest was 222 moves (Leela - Houdini, game 47, draw).

Time per game (hours)


Median= 3:06
Average= 2:57

Openings

There were 8-move book openings in this stage chosen by Cato. The first letter of the ECO codes was distributed as follows:


The engines had almost no freedom to choose the opening variant, 96.4% of the game pairs repeated the same ECO code and opening variant twice. In all of the game pairs the ECO first letter was repeated twice.

Reverse pairs, wins



The 2 "biased" openings involved Stockfish crashes - Stockfish won a game and crashed in the reverse. Not really biased openings... 

Reverse pairs, same moves 


Pairs of reverse games diverged very quickly, 47.6% diverged immediately out of book, 73.8% of the pairs diverged at most after 1 move. The longest repeated sequence of moves was 14 plys (Houdini - Leela games 75 and 103, Sicilian Scheveningen variation, Leela won in white)

 

Season 16 premier division after RR4

Crosstable after RR4

AllieStein continued with another extraordinary RR and it leads the table with a gap of 1.5 points. It scored +3 in RR4 beating all 4 bottom half of the table and losing once to Stockfish. It completed 3 double wins in the last two RRs, more than all the other engines combined so far. Stockfish and Leela both scored +1 and are tied in second place.

Stockfish survived RR4 without a crash, it is still one crash away from disqualification and there are two more RRs to go.


Leela is the only engine without loss so far, yet it has only 5 wins and only 4 against the engines in the bottom half of the table. Leela's win rate is low compared to its rivals, Stockfish and AllieStein have 8 wins so far (not counting AllieStein's "win" through a crash).

A few interesting games

Houdini - AllieStein: Material was equal and evals became negative though Houdini had a central passer. The game reached a QBB vs QBN position, the white king was exposed and AllieStein used this to capture two pawns. After exchanging queens and a few pawns AllieStein started to push a pair of connected passers, the game was adjudicated when they reached the 3rd rank.

Houdini - ScorpioNN: After almost 60 moves ScorpioNN was up a rook for a bishop, then it blundered and gave Houdini a strong attack on the black king. Houdini used the attack to gain material, it reduced to a QN vs QB position with 3 pawns up, the game reached a tablebase win.

AllieStein - KomodoMCTS: AllieStein's eval jumped over 2 early in the game. The engines exchanged pieces until only QRB vs QRB remained and then started to shuffle. After exchanging queens the black pieces had to protect pawns, AllieStein slowly walked its king to the queen side. KomodoMCTS let go of one pawn and AllieStein created an advanced passer and reduced to a rook ending. The game was adjudicated with AllieStein 4 pawns up. AllieStein won this opening from both sides.

Stoofvlees - AllieStein: AllieStein pushed pawns on the king side and (negative) evals started to increase. Both kings were exposed, Stoofvlees tried to attack the black king but AllieStein defended easily. The game reached a RBN vs RBN position with equal material, AllieStein used a mate threat to win material and reduce to a N vs R ending with two advanced passers. The game ended in a winning tablebase position. Another double win for AllieStein.

Komodo - Stockfish: The game reached an unusual R vs BNN ending, Komodo with 2 pawns and Stockfish with none. Stockfish's Eval was close to (negative) 3, but it couldn't find a way to win. The game ended in a draw after a long shuffle.

Stockfish - AllieStein: see featured game below.

Leela - Houdini: Houdini concentrated on the queen side and neglected its king, Leela's eval jumped over 1. Houdini captured a pawn but Leela's king side attack became dangerous. The engines exchanged pieces until only RB vs RN remained, Leela had a pair of connected passers in the center and the black king was almost trapped. It took a while before Leela captured two pawns and the game was adjudicated.

Stoofvlees - ScorpioNN: Stoofvlees pushed its king side pawns forward and left its king exposed. ScorpioNN gave a pawn and attacked, Stoofvlees exchanged pieces as evals increased. ScorpioNN had a chance of reducing to a drawn queen ending, instead Stoofvlees went two pawns up and its king escaped the checks. Stoofvlees pushed a pawn to the 7th rank and the game was adjudicated.

ScorpioNN - AllieStein: ScorpioNN blundered just before all the pieces were exchanged. One bad move with its king led to a king and pawn endgame that was a win for black. AllieStein was able to promote a pawn first, an easy win. A third double win for AllieStein.

Featured game: Stockfish - AllieStein
Premier division, game 102
Link to game on TCEC

There were very few exchanges after the opening. Stockfish gave a pawn and weakened the black pawn line, evals jumped over 1.5. AllieStein had a pawn majority on the king side and both kings were exposed.

AllieStein pushed pawns on the king side and tried to attack the white king. Stockfish got the pawn back and hid its king behind a black pawn on the 2nd rank. 

The white king was safe, AllieStein had to worry about its own king surrounded by pieces without pawn support. Stockfish slowly arranged its pieces, it still had to be careful to block back rank attacks. The pressure on the black pieces increased.

AllieStein's defense collapsed and Stockfish soon had the black king in a mating net and the game was adjudicated.

Season 16 premier division after RR3

Crosstable after RR3

AllieStein had an outstanding +4 score in RR3 and it leads the table. Leela scored +1 in RR3 with a quality win against Stockfish, Leela and Stockfish are tied in second place. Komodo and Houdini are not too far behind, each has only lost once but they are not winning games fast enough to join the leaders.

At the bottom of the table KomodoMCTS and ScorpioNN continue to be the punching bags of the division.

Stockfish is the source of more drama in the division. It crashed for the second time in this RR, this time against AllieStein. Stockfish is now one crash away from being disqualified, and with 21 games to go after 2 crashes in the first 21 games this is quite likely. The TCEC organizers asked the engine authors whether they agree to let Stockfish fix the faulty binary that is causing these crashes. The vote was anonymous and one author was against, this was considered as a veto and the suggestion fell.
My personal opinion is that Stockfish should not be fixed, these are genuine crashes even if they are not the 'fault' of the authors. Compilation and linking problems are a part of the process, and all engines have to deal with them. It would be disappointing if Stockfish were disqualified, it is doing very well in this division and it is in joint second despite two crashes. If it manages to survive the division it may yet reach the superfinal.

A few interesting games

Stockfish - Stoofvlees: Stockfish gave a rook for a bishop early, yet evals gradually increased. The white pieces were very active and eventually Stockfish captured the other black bishop and the game reached a RBN vs RR position. Stoofvlees had to protect its pawns, Stockfish used the extra piece to capture a pawn and create a passer. Stoofvlees couldn't prevent the pawn from promoting and the game ended with mate on the board.

KomodoMCTS - AllieStein: AllieStein went up a pawn early in the game. KomodoMCTS gave a second pawn and tried to attack, it forced the black king to the center but AllieStein's defense was strong enough. The game reached a RB vs RB position, material was equal but AllieStein had an passer on the 3rd rank. KomodoMCTS had to give the bishop to stop the passer, a win for AllieStein.

Leela - Stockfish: See featured game below.

Stockfish - ScorpioNN: ScorpioNN gave a pawn to create a passer, then pushed the passer to the 3rd rank. After some shuffling ScorpioNN tried to force an attack, it gave a rook and added a second connected passer on the 3rd rank. Stockfish remained calm, it reduced to a RRN vs RB position and captured one passer while the other reached the 2nd rank. The white rooks attacked ScorpioNN's king and soon had it trapped on the back rank. The game ended with mate in the PV.

AllieStein - Stoofvlees: Stoofvlees gave two pieces to push a pawn to the 2nd rank. AllieStein attacked the king side and the position became wild, with pins and threats and pieces offered and not taken. AllieStein gave a knight back, its eval increasing rapidly while the position stabilized. Stoofvlees lost a queen for a rook and bishop, the game reached a QN vs RN position. The queen was too strong despite the black passer still on the 2nd rank, AllieStein soon reduced to a tablebase win.

Houdini - KomodoMCTS: In a closed position Houdini gave a bishop for two pawns and created connected passers on the queen side. It pushed a pawn to the 7th rank and KomodoMCTS could only block it with its queen. It took Houdini a while to set up its pieces, eventually it managed to trap and capture the black queen. KomodoMCTS' defense collapsed and it lost a few moves later.

ScorpioNN - KomodoMCTS: ScorpioNN was a pawn up in a closed position. It seemed to have the advantage and was close to a first win in the division, but it couldn't find a way to improve. The engines exchanged pieces until reaching a tablebase draw.

Komodo - ScorpioNN: The game reached a RBB vs RBN position, Komodo a pawn up. The engines mostly shuffled for a very long time and both played on the increment. Komodo traded a bishop for a knight and then found a way to trap the black king and bishop. ScorpioNN could only watch as Komodo moved its king forward, the game ended in a rook ending tablebase win.

AllieStein - Stockfish: The engines shuffled in a QRB vs QRB position, and with the 50-move counter down to 10 Stockfish crashed.

Leela - KomodoMCTS: The black king was trapped in the corner, KomodoMCTS used this to draw by threatening stalemate. Leela may have had a chance for a moment, but in the end the game ended in a draw after 206 moves.

AllieStein - ScorpioNN: The game reached a RB vs Q position, AllieStein pushed a pawn to the 7th rank and the engines started to shuffle. It took AllieStein a long time to find a way to improve, ScorpioNN moved pawns on the queen side and this let AllieStein create a second passer which won the game.

Featured game: Leela - Stockfish
Premier division, game 64
Link to game on TCEC

Leela started the game with an eval around 1 that increased gradually. Stockfish kept its king in the center, the king side rook and bishop were trapped. There were two open files on the queen side that Stockfish had to watch, its king had no escape if Leela attacked through there.

Leela was very patient, the black pieces were passive and Leela took a long time to arrange its pieces. The black bishop protected the g7 pawn and did not move, the black rook moved a few times so castling was not an option for Stockfish.

On move 53 Leela was ready. It forced a knight for bishop trade and then captured the g7 and a6 pawns. The game reduced to a RB vs RN position, Leela was two pawns up and it had two passers on the queen side.

Leela created a second passer on the king side and adjudication was a matter time. This was Stockfish's first loss in the division which was not a crash.

Season 16 premier division after RR2

Crosstable after RR2

After the first double RR is over the top of the table is what we have seen in the last few seasons, with Stockfish in front and Leela second, already with a small gap to the other engines. Both Stockfish and Leela had a +1 score in RR2, not very high but still no other engine scored better and this was enough to keep them in the lead.

At the bottom KomodoMCTS and ScorpioNN continue to lose games to all other engines, they are surely on their way to league 1.

There was an unusual Stockfish crash. It happened in a drawn position in the game against Houdini, so Houdini has not won a real game yet and it would have had a negative score if Stockfish hadn't crashed. The Stockfish developers think the crash may have been the result of a problem in an external library, not the Stockfish code. This means that such a crash might happen again. A rate of one crash in 2 RRs could be too high and Stockfish might be in danger of disqualification.

A few interesting games

AllieStein - KomodoMCTS: AllieStein had a significant eval advantage with even material, perhaps due to an active bishop pair in an open position and the exposed black king. AllieStein's eval peaked over 10, it was a pawn up and the game reduced to a RN vs RN position. KomodoMCTS found a defense by giving checks and using a mate threat, the game reached a drawn rook endgame.

KomodoMCTS - ScorpioNN: The position looked drawn when ScorpioNN allowed KomodoMCTS to reduce to a king and pawns endgame. Both engines managed to promote a pawn to a queen, KomodoMCTS was a pawn up and this was enough to force a win. First win for KomodoMCTS in the division.

Stockfish - AllieStein: The engines shuffled in a closed position and were close to a 50-move draw twice. Evals started to increase with very little time left, the game reached a RN vs RB position. AllieStein was a pawn up but Stockfish had an advanced passer supported by the king and its pieces were much more active. AllieStein couldn't stop the passer without losing a piece, and the game was adjudicated.

Stoofvlees - ScorpioNN: Stoofvlees had an eval around 1 from the start. The game reached a QRB vs QRB position, Stoofvlees had a strong pawn line while ScorpioNN had a trapped bishop and two isolated pawns on the queen side. ScorpioNN gave two pawns and tried to attack the white king. In desperation ScorpioNN sacrificed a rook but couldn't force a perpetual check, Stoofvlees' material advantage gave it the win.

KomodoMCTS - Leela: Leela pushed a pawn to h3, its signature thorn pawn move, and its (negative) eval went over 1. It captured a pawn and created a passer on the queen side, while KomodoMCTS had a passer in the center. The engines got rid of the passers and reduced to a RB vs RN position, Leela captured another pawn and that was enough for a win. Two wins for Leela in this opening.

Houdini - Stockfish: The game reduced to an opposite color bishop ending and was heading for a draw when Stockfish crashed.

AllieStein - Komodo: See featured game below.

Stockfish - KomodoMCTS: Stockfish castled long, then gave a rook for a knight early and opened the king side. The black king walked to the queen side to find safety, the engines reduced to a QR vs QR position with Stockfish two pawns up. After exchanging queens the white passers won the game.

Featured game: AllieStein - Komodo
Premier division, game 52
Link to game on TCEC

AllieStein was up a knight for a pawn early in the game. Komodo's rooks controlled the center files and its queen threatened the exposed white king. However, Komodo's attack was not strong enough to compensate for the piece.

AllieStein's eval increased rapidly as the engines exchanged pieces until reaching a QBB vs QN position, with AllieStein two pawns down. The LS bishop was restricted by the black pawns and knight.

Komodo pushed its king side pawns and tried to blockade the white bishops and king. After a while AllieStein forced a queen exchange and only BB vs N remained.

The white bishops targeted the black pawns, they slowly cleared a few and made more space for them to move. Komodo defended for more than 30 moves but eventually agreed it was losing and the game was adjudicated. This is the first loss for Komodo in the division.

Season 16 premier division after RR1

I'm back from sick leave and gradually getting better. It is going to be hard work to catch up with all the games played so far in the premier division, but we'll get there eventually.

Crosstable after RR1



Stockfish is leading the table with a +3 score. Leela and Komodo are close behind with +2, Komodo doing better than expected in the first RR.

At the bottom are KomodoMCTS and ScorpioNN, with a total of 7 losses of 12 games against the other 6 engines. Only Houdini does not have a win against at least one of them.

Stoofvlees is the only engine with at least one win and one loss.

TCEC has a new web page which is supposed to be more stable. The live engine analysis appears only in the new website. There is also a new archive and the premier division games can be found only there. Here are the addresses:
New site: https://tcec-chess.com/
New archive: https://www.tcec-chess.com/archive.html
 
A few interesting games

Leela - ScorpioNN: Leela was up a pawn in a QRR vs QRR position. It gave the pawn back and created a passer, evals climbing over 2 at this point. A pawn exchange later Leela had two connected passers on the queen side and ScorpioNN also had to protect its king. The engines exchanged queens and the double rook ending was a win for Leela.

Stockfish - Stoofvlees: See featured game below.

Komodo - KomodoMCTS: Most of the black pieces were on the queen side when Komodo started attacking on the king side. It gave a knight to open a file, KomodoMCTS' king had to face all the white major pieces almost without support. KomodoMCTS gave its queen for a rook to save its king, the game reached a Q vs RN position and Komodo won.

KomodoMCTS - AllieStein: The game reached a RB vs RB position that appeared completely drawn. The engines exchanged bishops just before the 50-move mark, then exchanged rooks. Unexpectedly KomodoMCTS blundered the endgame, and AllieStein used zugzwang to capture two pawns and win.

Stockfish - ScorpioNN: There were only a few exchanges in the first 75 moves and evals stayed low. Stockfish gave two pawns and created a passer on the queen side, ScorpioNN eventually gave a knight to get rid of the passer. The game reached a QN vs Q position, Stockfish captured a pawn and then forced a queen exchange to get a tablebase win.

Komodo - ScorpioNN: ScorpioNN gave up a pawn for no apparent reason, perhaps it thought its king side pressure was some compensation. Komodo defended easily, captured a second pawn and pushed a passer to the 7th rank. ScorpioNN gave material to keep its attack alive, the game was adjudicated a few moves later.

KomodoMCTS - Stoofvlees: Stoofvlees developed a strong bishop pair and KomodoMCTS gave a rook to remove one of them. The game reached a difficult BN vs RB endgame with one pawn for each engine, Stoofvlees managed to capture the white knight after 30 moves and get a tablebase win.

Leela - KomodoMCTS: KomodoMCTS had initiative on the queen side, with a rook controlling an open file. It paid less attention to the king side, and when Leela opened a file there the black king was in danger. Leela increased the pressure and the black king fled to the center. Leela sacrificed a queen for a knight, KomodoMCTS had to give its queen to avoid mate, the RBN vs RN ending was a win for Leela.

Stockfish - Houdini: Stockfish gave a rook for a knight temporarily, then got the material back and created a passer. The game reached a QRB vs QRB position, after exchanging queens Stockfish pushed the passer to the 7th rank. Houdini had to give its bishop to stop the passer, leading to a won endgame for white.

AllieStein - ScorpioNN: AllieStein captured a rook for a bishop, its eval peaked close to 9 in a RB vs NN position. The engines started to shuffle and AlllieStein could not find a way to break ScorpioNN's defense. The game ended with a 50 move draw.

Featured game: Stockfish - Stoofvlees
Premier division, game 2
Link to game on TCEC

Stockfish went up a pawn on move 23 with a 3 to 1 pawn majority on the queen side, evals stayed below 1.


 
Stockfish pushed its queen side pawns forward and evals went up. Stoofvlees tried to counter with a passer in the center and pressure on the king side, it sacrificed a knight to expose the white king.

Stockfish calmly defended its king, Stoofvlees gave a rook for a bishop and increased the pressure but in the end the attack on the white king was not effective. Meanwhile Stockfish cleared the path for its pawns on the queen side.

The extra white rook together with one of the pawns queening led to a quick mate on the board for Stockfish.

 

Delay in posts on premier division

Due to a medical situation I am unable to write posts on the premier division at this time. Even writing this note using my phone is torture (technically speaking). I hope to get well soon and catch up.