Season 14 superfinal, games 11-14

After 14 games the result is 2-2 with 10 draws.
Leela equalized with two straight game pair wins. Stockfish's early lead is gone, and we have a real match this superfinal. 

Games 11-12 were a French opening variant, one of Leela's preferred openings. In game 11 Stockfish played unusual moves from the start, and Leela's eval was close to 2. The center and queen side were blocked, Leela shifted its pieces to the king side where it had a large space advantage. Stockfish saw the danger and its king started to walk to the queen side.


There was no contact between the opponents, Leela patiently arranged its pieces while evals increased. Stockfish tried to free its pieces by pushing the king side pawns, as a result the king side opened. All Stockfish could do was protect its pieces, it was almost paralyzed and too many black pieces were too far to help.


Leela continued to improve slowly. It created a passer on the g file and exchanged a pair of knights to get rid of a useful defender. Evals climbed fast though material was equal. Leela offered a rook for a bishop, Stockfish knew better since accepting would give Leela a second connected passer on the 6th rank.


Finally the tension was released with a series of exchanges starting on move 46, as a result Leela was a pawn up with two passers on the king side. A few moves later Leela won a second pawn and the game reached a QRB vs QRB position. Leela continued to move slowly, it wasn't looking for the fastest way to win. The game continued until move 76, it was adjudicated with Leela 4 pawns up. First win for Leela.

The engines played differently in the reverse game. The center and queen side were open and Leela castled short. Stockfish had an eval around 1 for 25 moves, but then it came down. Both engines had advanced passers, Leela captured a rook for a knight and Stockfish could end the game with a perpetual check. Instead the game continued, the engines exchanged pieces until only N vs R remained. Leela kept a small negative eval, both engines queened and the game was adjudicated only 40 moves later. Leela wins its first game pair of the match.

In game 13 Leela pushed pawns forward on both sides of the board without castling. The black pieces were pushed back, Leela had a significant space advantage and a small eval advantage despite its king in the center with only one pawn defender. It even managed to push a pawn to h6, kingcrusher's famous thorn (fawn?!) pawn.


Stockfish broke through the queen side, giving a rook for a bishop and two pawns. Leela's eval jumped over 2 while Stockfish still felt safe. 


The engines exchanged pieces gradually and Stockfish's eval started to climb. The game reached a RN vs BN position on move 40, Stockfish was up 3 pawns but its king and pieces were far away and the queen side pawns looked weak.


Stockfish traded two pawns, which left Leela with only one. However it was a queen side passer and Stockfish could only stop it by losing its knight. The black pawns did not compensate for a rook, a win for Leela. 

In the reverse game Stockfish castled its king and didn't push pawns forward. Evals came down to 0, and Leela's eval turned negative on move 27 with almost all pieces still on the board. The engines exchanged pieces gradually, by move 54 only QRN vs QRN remained and the quuen side pawns were all gone. The game was adjudicated a draw on move 87.

Season 14 superfinal, games 1-10

The season 14 TCEC cup is over, Leela is the winner. Leela had a long semifinal match against Komodo, after 16 consecutive draws Leela beat Komodo from both sides of an opening to win the match. The second semifinal between Houdini and Stockfish was also long, after 11 draws Houdini beat Stockfish after drawing the reverse. Stockfish's loss was surprising, though Houdini has shown it can be better in shorter time controls. I don't think there is doubt that Stockfish is better than Houdini, even if it loses games on occasion. In the final Houdini and Leela started with 7 draws, and another long match was expected when Leela beat Houdini in the 8th game and won the cup.

This season Leela has shown that it can compete with the best engines, better than I anticipated after the previous season. Stockfish was clearly better in the premier division, but Leela gets better from event to event. This superfinal should be exciting, the engines have different playing styles and different approaches to evaluation.  They may make moves that surprise their opponent as well as the spectators. I hope we see exciting draws, wins for both engines and a close result.

After 10 games Stockfish leads 2-0 with 8 draws.

Games 1-2 started with white a pawn up and the center pawns cleared. Game 1 reached a R vs BB imbalance on move 26 after a series of exchanges. Leela was two pawns up with a queen side passer, its eval was over 1 for a long while. Stockfish's eval dropped to 0, the engines mostly shuffled in a RN vs BBN position. Eventually after more exchanges Leela's eval dropped to 0 as well, the game ended in a tablebase draw on move 131. In the reverse Stockfish had an eval over 1 for 40 moves, the game reached an BN vs R imbalance with more pieces on the board, but reduced to a BN vs R position later. Leela had a queen side passer and evals dropped to 0 as it pushed it forward. After a long shuffle Stockfish countered with a passer on the king side, the game reached a tablebase draw on move 116.

In game 3 queens were off early, the engines gradually exchanged pieces until reaching a rook ending on move 36. Leela had a pair of connected passers on the queen side and it remained hopeful for a while. Stockfish countered with its pawns on the king side, and this was enough to hold a draw. In game 4 Stockfish had a small eval advantage, there were several early exchanges but the queens stayed on the board until move 30. The engines targeted the pawns, and by move 37 only two pawns were left for each engine. Evals dropped to 0, Stockfish could close the game with a perpetual check but changed its mind at the last move. In the end the draw rule adjudicated the game.

Leela's eval jumped over 1 after a few moves in game 5. It exposed the black king and pushed pawns on the king side. Stockfish exchanged pieces to stop the attack, then gave a knight for two pawns and reduced to a BN v B ending. Leela needed 30 more moves to lower its eval, the game ended in a tablebase draw. Stockfish started game 6 with an eval advantage,but its eval dropped to 0 by move 22. Leela's eval became negative, it threatened the white king on the queen side and Stockfish's pieces had less space to move. Stockfish reduced to a rook ending, and 40 moves later the game ended in a tablebase draw.

Games 7-8 were a King's Gambit variant, both started with black a pawn up and a significant eval advantage. In game 7 Leela castled short and Stockfish pushed its king side pawns forward. Leela pushed pawns on the queen side and captured a free pawn, but it delayed the development of the queen side pieces. Stockfish thought Leela's 15th move was a blunder, its eval jumped over 1.5 as it used its king side pawns to expose the white king.


Leela gave a rook for a bishop and Stockfish's eval was already over 4. Stockfish gave a knight and pawn, leaving the white king almost defenseless. The black major pieces joined the attack while most of the white pieces were still stuck on the wrong side of the board.


The white king was under mate threats and fighting for its life. Leela barely managed to defend, eventually exchanging pieces to save its king. The game reached a R vs RB position, black with two passers on the king side. The attack on the king was over but evals were close to 10.


There was no doubt Stockfish was winning. Due to a configuration bug the game continued beyond the normal win rule, the rooks were exchanged and white couldn't stop all the marching pawns. First decisive game of the match, with some help from the biased opening.

In the reverse game Stockfish castled long and kept its king safe. Leela kept the pawn advantage and had an eval of over 1 that constantly increased. The engines exchanges all major pieces by move 25 and Leela's eval was around 4. Stockfish's eval slowly increased, it seemed that Leela was slowly improving. The game reached a BBN vs BBN position with stable pawns, Leela just needed to find a way to capture a pawn and the white defense would collapse. Then suddenly Stockfish's eval dropped, it exchanged a bishop for a knight to get this position:


Leela's LS bishop had no targets and its DS bishop was blocked, Stockfish could keep the black king away,  a perfect fortress. Leela conceded the draw 70 moves later. A lucky escape for Stockfish, disappointment for Leela.

Leela started game 9 with a small eval advantage. Stockfish's eval was close to 0 after a few moves and stayed there throughout the game. The engines exchanged pieces and pawns gradually, by move 38 only QRB vs QRB remained. Leela's eval came down, but when it captured a pawn and reduced to a bishop ending its eval jumped over 2. Stockfish had an advanced passer, Leela gave its bishop to take it. That left two white passers, Stockfish's bishop and king were on time to stop them, the game ended in a draw.

The start of game 10 was similar, Stockfish started with an eval advantage and the engines opened the center. Stockfish's eval jumped over 1 as it captured a pawn on the king side and exposed the black king. Leela exposed the white king in return, and then Stockfish allowed the black king to capture its bishop.


Evals started to jump as Stockfish attacked the king side with all available pieces. The black king was in the open and there were not enough black defenders. In a few moves the black king was trapped and several black pieces were pinned down, evals were over 4.


Stockfish got the piece back for a pawn. Leela managed to get its king to safety on the queen side but it lost another piece in the process. The game reduced to a QRB vs QR position, black two pawns up.


Leela tried to counterattack the white king, this delayed the end a little. When the checks stopped the black king was in trouble again, the game was adjudicated before Leela lost more material.

Season 14 premier division final results

Final crosstable


KomodoMCTS was disqualified after crashing 3 times, its games do not count. As a a result the relevant standings are:
Stockfish +14, Leela +4, Komodo +3, Houdini +2, Fire -6, Ethereal -8, Andscacs -9.

Stockfish and Leela qualify for the superfinal of season 14. Stockfish was the clear leader of the division. The fight for 2nd place was very close and was decided only in the last game played. I was surprised by Leela's achievement, it is improving very fast and it is possible that the version that will play in the superfinal will be even stronger. Houdini is still waiting for an update to get better. Komodo is also losing ground, but there is new hope with its relative KomodoMCTS. If it was stable it would have been better than Fire, and the developers claim it is improving all the time. Perhaps it will replace Komodo in the next season.

KomodoMCTS is relegated due to crashes. Andscacs and Ethereal were very close through the RR and the second relegated engine was decided in the last round where Ethereal held and Andscacs lost. Ethereal survives the premier division this season, but it will need a significant improvement to have a chance in the next.

The superfinal will only start in a few weeks time. TCEC will first hold its second cup event where we may see a first glimpse of a newer and better Leela. I will not be covering the cup games and my coverage will return for the superfinal games.

A few interesting games

Komodo - Stockfish: See featured game below.


Leela - Fire: Leela's eval jumped close to 2 from the start, after a series of early exchanges only RBN vs RBN remained on move 18. Fire had two isolated pawns on the queen side, after exchanging bishops Leela captured both while Fire captured pawns on the king side. Leela pushed a queen side passer to the 6th rank, forcing Fire to defend and leave the king side pawns without support. Leela reduced to a knight ending two pawns up for the win. There were two white wins in this opening.

After 3 rounds the table is: Stockfish +13, Leela +4, Houdini +2, Komodo +1, Fire -5, Ethereal -7, Andscacs -8. Stockfish, Komodo and Ethereal have 4 games to play, the other engines only 3.

Komodo - Fire: Fire's king remained uncastled in the center, the queen side was exposed and when Komodo pushed pawns on the king side the black king had no safe place to go to. Evals gradually increased as the black pieces were pushed back. Fire countered on the queen side where the white king was, its pawns were blocked on the 3rd rank. After a few exchanges Komodo managed to infiltrate the queen side and capture a pawn, then it reduced to a RB vs RB ending. Fire was not convinced it was losing, only after Komodo captured a second pawn and the passers started to march Fire's eval was high enough for adjudication.

Stockfish - Ethereal: The game reached a RRB vs RRN position with low evals. Then evals started to increase as Stockfish slowly outplayed Ethereal. After exchanging a pair of rooks Stockfish captured a pawn, several moves later Stockfish created a queen side passer. The passer started to march and eventually Ethereal lost material to stop it, giving Stockfish the win.

Leela - Andscacs: The center and queen side were blocked, Leela moved its major pieces to the king side and threatened to break through, its eval climbing fast. Andscacs castled short, then walked its king to the queen side in face of the danger on the king side. Leela opened a file on the king side and doubled its rooks, its eval over 4.5. The engines shuffled for a while, then exchanged all rooks. Leela's eval peaked over 5 after it captured a pawn, then Andscacs exchanged down to a same color bishops ending and evals dropped. Leela had a passer but Andscacs defended well, the game continued until move 173 before it was adjudicated a draw.

After 5 rounds the table is: Stockfish +14, Leela +4, Houdini +2, Komodo +2, Fire -6, Ethereal -8, Andscacs -8. Stockfish, Houdini, Komodo, Ethereal and Andscacs have 2 games to play, Leela and Fire only 1. Fire is almost surely safe, Andscacs beat Ethereal once so it has the tiebreak advantage. Houdini and Komodo need two wins to catch up with Leela, and Leela might lose the last game black against Stockfish. 

All 4 games in round 6 ended in a draw, table is unchanged. Fire has a 1 point lead over Andscacs and Ethereal. It does not play in the last round but it has a tiebreak lead over Ethereal so it is safe. Ethereal needs a a better score than Andscacs to stay in the division. Leela will be second if it does not lose. If it loses both Houdini and Komodo can catch up it if they win, but only Komodo has a tiebreak lead over Leela.

Houdini - Ethereal: Houdini had a space advantage and eval over 1. The center was blocked and there was a possibility of a king side attack. Ethereal somehow held the position with minimal pawn support for its king. Houdini could only shuffle and exchange pieces, the game ended in a B vs N drawn position.

Komodo - Andscacs: Komodo had an eval advantage from the start, Andscacs held it below 1 for the first 30 moves and then it started to increase. Komodo created a queen side passer and pushed it to the 5th rank, there it was blocked by black pieces. Andscacs refused to capture a rook for a bishop as that would give Komodo a second connected passer. Komodo was in control, Andscacs had to defend its back ranks and Komodo captured a pawn. The game reached a QRB vs QRB position and Komodo pushed its passer to the 7th rank. The game was adjudicated after the queens were off and Komodo was two pawns up.

Ethereal survives and Andscacs will be relegated. Komodo and Leela are tied in second place before the last game of the division, if Leela loses Komodo will finish ahead of Leela.

Stockfish - Leela: Stockfish sacrificed a knight for a promising attack on the exposed black king. Evals reached over 1, Leela exchanged pieces and evals came back down. The game reached a rook ending that ended in a draw.

Leela survives the last game and qualifies for the superfinal.

Featured game: Komodo - Stockfish
Premier division, round 37
Link to game on TCEC

Komodo had an eval over 0.5 from the start. Material was equal, Komodo had a space advantage and it created a central passer. Stockfish's position looked solid enough and the evals remained more or less constant.

The engines slowly exchanged pieces, Komodo's eval advantage held for 30 moves and then went down. Stockfish pushed its king side pawns and took the initiative, forcing the white pieces back. It created a pawn line that ended on g3 and trapped the white king in the corner, its eval became negative over 1.

The engines shuffled for many moves. Komodo was careful not to allow the black f pawn to advance, Stockfish slowly moved its pieces to the queen side and doubled rooks on the a file. The draw counter was down to 8 when the engines exchanged a pair of rooks, evals started to jump. 

Komodo avoided exchanging the queens, its king was trapped in the corner and white would have a significant advantage if it could move its king forward. Stockfish used a threat of a back rank mate to win a bishop, the game was adjudicated with the PV showing Komodo losing more material. A double win in this opening for Stockfish.

Season 14 premier division statistics

A summary statistics table of previous stages and seasons. 

Draw rate, wins

 
Final draw rate was 71.4%.
The KomodoMCTS - Leela game in round 34 crashed due to network problems and was not replayed. I am counting it as a draw.


Game termination

The three most common game termination causes were:

33.9% - TCEC draw rule
25.6% - SyzygyTB
24.4% - TCEC win rule

KomodoMCTS crashed 3 times in the division and was disqualified. One Leela game was stopped due to a network failure.

Moves per game

 
Median= 64.5
Average= 74.6

There were 29 games longer than 100 moves, the longest was 209 moves (Fire - Leela, round 17, draw).

Time per game (hours)

 
Median= 3:03
Average= 2:59

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 8-move book determined the opening in almost all cases, 97.6% of the game pairs repeated the same ECO code twice, 97.6% repeated the same opening variant. All of the game pairs repeated the ECO first letter twice.

Reverse pairs, wins

 
Reverse pairs, same moves 

 
Pairs of reverse games diverged very quickly, 52.3% diverged immediately out of book, 78.6% of the pairs diverged at most after 1 move. The longest repeated sequence of moves was 11 plys (Ethereal - Stockfish, rounds 33 and 40, QGD, Stockfish won as white and drew as black).     

Season 14 premier division after RR5

Crosstable after RR5


After 2 clean RRs KomodoMCTS crashed for a third time and was disqualified. It keeps playing but the results of all its games in the division will be ignored. As a result the actual crosstable is not as it appears in the live and archive sites. After 5 RRs the standings are: 

Stockfish +12, Leela +3, Komodo +2, Houdini +2, Fire -4, Ethereal -7, Andscacs -8.

Stockfish is still unbeaten in the division and will qualify for the superfinal. Leela, Komodo and Houdini are fighting for the second spot with Leela 0.5 point ahead. Leela lost twice in this RR, its worst RR so far in the division. This allowed Komodo and Houdini to get close and now the race is very close and every game counts.

KomodoMCTS was disqualified and it will be relegated back to division 1. The other engine to be relegated is one of Ethereal and Andscacs. Fire is still in danger but has a comfortable gap of 2 points from last place. Ethereal has no wins in the division yet it is 0.5 points ahead. The engine that loses less games will survive.

Leela suffered 3 losses in 4 games, including one from the previous RR. This led to a check of the GPU hardware and it was found that there was a problem with the GPU fan setting. However this problem probably started from division 3, recall that Leela won 3 divisions convinvingly and it is close to reaching the superfinal in the premier division. As a result the organizers decided against replaying any games.

There were a few one-sided openings in this RR, the reverse games should be exciting to watch.

A few interesting games

Stockfish - KomodoMCTS: Stockfish had an eval advantage of about 1 from the start, and it gradually increased. The black pawn line was mostly on the 6th and 7th ranks, leaving very little room for the pieces to move. Stockfish attacked on the king side, KomodoMCTS surrounded its king with pieces so that it was vulnerable to knight threats. In a series of exchanges Stockfish won a bishop for pawns, later KomodoMCTS lost a knight to avoid mate and the game was adjudicated.


Komodo - Leela: See featured game below.

KomodoMCTS - Ethereal: KomodoMCTS had an eval over 1 despite being a pawn down. KomodoMCTS regained the pawn and the engines exchanged down to a double rook ending. Ethereal's pawn structure was weak, KomodoMCTS captured a pawn and created a majority on the king side. Then it exchanged a pair of rooks and captured a pawn on the queen side, leading to a won rook ending.

Leela - Houdini: Leela's eval was over 1 and increasing from the start. It had a pawn majority on the queen side that later became a passer on the 7th rank. Houdini gave a rook for a bishop to get rid of the passer and the game reached a RB vs BB position. Leela's eval peaked over 4 while Houdini's eval remained below 1. Leela tried hard but couldn't break Houdini's defenses, the game ended in a draw.

Stockfish - Komodo: After a series of early exchanges Stockfish was up a pawn and had an eval over 1.5. The engines played out a long PV agreement that ended in a RB vs R position, Komodo two pawns up. It took Stockfish a while to convert the win. After a few pawn exchanges the white rook got behind the black pawns and started to attack them. The game was adjudicated before Stockfish started to push passers on the king side.

Komodo - KomodoMCTS: KomodoMCTS went a pawn up after several early exchanges, Komodo's eval was over 1 and increasing. In another series of exchanges Komodo won a knight and the game reduced to a RN vs R ending. KomodoMCTS saw it was losing and it gave up, letting Komodo capture its pawns and rook.

Fire - Leela: Fire had an eval advantage from the start, Leela's eval jumped over 2 very early while Fire's eval was below 1. Material was equal and the engines exchanged pieces, Fire went a pawn up only on move 30, Leela's eval was already over 7 at this stage. The game reached a knight ending and the pawns raced forward. Leela promoted first but Fire promoted with a check and had a second pawn on the 7th rank. Leela could give a few checks but this only delayed the adjudication.

Stockfish - Andscacs: Stockfish had an eval advantage from the start, its eval remained under 1 for the first 35 moves. Andscacs captured a pawn and the position opened up, Stockfish's eval jumped over 2. The black king was vulnerable to attack, Andscacs was busy protecting it and Stockfish used this to capture black pawns. The game reached a RN vs RB position with Stockfish 2 pawns up and the game was adjudicated after several more moves.

Featured game: Komodo - Leela
Premier division, round 29
Link to game on TCEC

Evals were close to 0 at the start of the game, even after Leela went a pawn up. The engines castled in opposite directions, Komodo moved its pieces to the queen side facing the black king and evals started to increase.


Leela offered a rook for a bishop for a few moves and its eval jumped oveer 1.5. Komodo waited for the right moment to take the offer, then the engines reduced to a QR vs QN position and Komodo's eval jumped over 2.



Both queens captured pawns, Leela cleared the king side and Komodo cleared the queen side. Komodo's eval slowly increased but Leela thought it was much safer than before. Leela's pawns had a head start but Komodo's king side pawns had a clear path, Komodo also had a rook on the back rank for protection. Leela was late in realizing it was heading for a loss.



Komodo's h pawn ran fast and queened. Leela also queened a pawn but lost one queen for the white rook. In the end Komodo had two queens to Leela's one, it was close to mate when the game was adjudicated.

Season 14 premier division after RR4

Crosstable after RR4


Stockfish remains in the lead with a +3 score in this RR. Leela had a great RR with 4 wins, and despite losing a game to Stockfish (first loss in the division) it extends the gap to 1 point from 3rd place. Komodo and Houdini are still in the race, they need wins and/or luck to overtake Leela.
KomodoMCTS continues to survive and not crash. Ethereal scored -4 in the RR and drops to the bottom of the table joining Andscacs. Fire is 1 point ahead of the relegation zone and is not in the clear yet.

A few interesting games

Andscacs - Houdini: Houdini's eval was negative from the start. Andscacs opened a file on the queen side and placed a rook on the 7th rank, Houdini sacrificed a knight for pawns and created a pair of connected passers. The engines exchanged pieces and Andscacs gave back the knight to remove one of the passers. This left a double bishop ending with Houdini a pawn up. The white king walked to the queen side to stop the passer, the black king captured a pawn on the king side and secured the win for Houdini.

Stockfish - Houdini: Stockfish's eval was close to 1 from the start. Houdini pushed pawns on the king side, leaving its king without pawn support. Stockfish pushed pawns on the queen side, all pawns remained on the board until move 33 when Stockfish opened the queen side. Evals were over 2, Houdini opened the king side and created a little space for its pieces, exposing the king to attacks. Stockfish gave a rook for a bishop, but with all its pieces targeting the black king Houdini could not hold. The game was adjudicated with PVs showing how Stockfish can reduce to a winning endgame.

Leela - Fire: Leela's eval was over 1 and increasing from the start. Fire opened a file on the queen side and controlled it with major pieces, Leela covered its back ranks and did not allow Fire to attack from there. Meanwhile the black pawns blocked one of Fire's bishops, and Leela pushed pawns on the king side and trapped the second bishop in the corner. Fire was paralyzed, though it took a while to recognize it was losing. Leela had all the time in the world first to exchange queens and then to walk with the king to the queen side and drive away the black rook. In despair Fire gave a bishop to break the blockade, a white passer forced Fire to lose more material and the game.

Ethereal - Leela: Leela's eval was negative from the start, it kept its king in the center and blockaded the center and king side with pawns, its eval gradually increased. A pawn exchange opened a hole on the queen side, the black king walked to safety on the king side and Leela moved pieces to the queen side. Another pawn exchange created a queen side passer for Leela and Ethereal's eval started to increase as well. Leela pushed the passer to the 3rd rank and slowly increased the pressure, until Ethereal gave a rook for a knight to capture the passer. Leela reduced to a winning R vs B ending.

Komodo - Fire: After several early exchanges queens were off, Komodo had a bishop pair advantage and an eval over 1. Fire reduced to an opposite color bishop ending with Komodo a pawn up. The white king was better placed than the black king, allowing Komodo to capture a second pawn. Komodo was able to convert this advantage to a win.

Stockfish - Ethereal: Stockfish's eval was over 1 a few moves after book though material was equal. As the board cleared up it became evident that Ethereal's pawn structure was weak. Stockfish focused on the backward d6 pawn and Ethereal put both rooks behind it to defend. In a RRN vs RRN position the h6 pawn became a second target. Ethereal's pieces were not fast enough to defend both pawns and Stockfish captured the h6 pawn. The game reduced to a knight ending, Stockfish captured a second pawn and the game was adjudicated.

Leela - Andscacs: Andscacs pushed its king side pawns in front of a castled king. Leela kept its king in the center, then pushed a pawn to h6 with its eval jumping over 2.5. Leela attacked the king side pawns and weakened their structure, Andscacs remained calm and was sure in its defense. Leela's king walked to the queen side, its eval increasing though it seemed Andscacs was holding. The game reached a RN vs RB position, it took Leela a long time to find a winning path. It captured a pawn and reduced to a winning rook ending. A double win for Leela for this opening.

Leela - KomodoMCTS: Leela had an eval around 1 from the start. The engines opened the queen side, KomodoMCTS had an isolated pawn in the center. Leela's eval jumped over 4 when it exchanged a bishop for a knight and created a pawn majority on the king side. The engines shuffled for a long time, Leela reduced to a RN vs RB position on move 78. It delayed the king side push to move 104, this created a passer that cost KomodoMCTS a bishop and the game was adjudicated.

Ethereal - Komodo: Ethereal started with a small eval advantage, Komodo equalized and evals came down to 0 despite Ethereal being a pawn up. The engines exchanged down to  QRB vs QRN position, but one move before adjudication by draw rule evals became negative. Ethereal exchanged queens and Komodo regained the pawn, evals stayed below 1. Ethereal pushed a pawn and queened it, giving its other pieces and leaving a Q vs RN position Komodo 2 pawns up. Evals remained low for a while, then Ethereal blundered and evals jumped. Komodo connected its pawns and its king, surrounded by its pieces. Two connected passers started to march and the game was adjudicated.

Houdini - Ethereal: Houdini had an eval advantage that gradually increased. There were almost no exchanges in the first 40 moves, Houdini's eval was over 3 as it increased the pressure on the queen side pawns in a closed position. The black pieces were busy defending the queen side, when Houdini opened the king side it won a knight and Ethereal's defense collapsed. The game was adjudicated before Ethereal lost more material.

Stockfish - Leela: See featured game below. First loss to Leela in the division.


Featured game: Stockfish - Leela
Premier division, round 28
Link to game on TCEC

Stockfish had a small eval advantage from the start, but it remained around 0.5 for the first 30 moves. Both kings were safe, there was one open file on the queen side that Leela controlled, the engines gradually exchanged pieces. On move 33 Stockfish offered a pawn but did not expect Leela to take. When Leela calmly took the pawn Stockfish's eval jumped over 2.


The PV showed that Leela saw the immediate tactic, it was losing a rook for a knight and pawns. However, it thought it had a perpetual check draw and missed Stockfish's 38.Bxb5 move. When it saw what happened Leela's eval jumped over 3. After several check moves the engines reduced to a QR vs QN position.


Stockfish captured the black b pawn and the pawn on the a file became a dangerous passer, though it was still far away from promoting. Leela countered with central passers of its own, Stockfish attacked the back ranks and threatened mate.


Leela's last resort was checks against the white king. The black queen chased the white king for more than 15 moves, while evals continued to increase. The game was adjudicated when the king approached the a8 corner, the support of the white pieces guaranteed a stop to the checks and a win for Stockfish.

Season 14 premier division after RR3

Crosstable after RR3

Stockfish continues to lead the table, it added two wins in the RR and has a +8 score, 2.5 points ahead of the competition. Leela is now in second place and is the second engine without loss. Komodo and Houdini are 0.5 a point behind, recall that Komodo benefited from two crashes.
KomodoMCTS limited the number of threads to 32 and hasn't crashed in this RR. With a +1 score this RR it is moving away from the relegation zone, one more crash and it is out though.
Andscacs won its first game of the RR, but with 3 losses it is at the bottom of the table and likely to be relegated. Ethereal is the only engine without a win, and with a -2 score in the RR it is tied with Fire in joint 7th place.

A few interesting games

KomodoMCTS - Ethereal: KomodoMCTS pushed pawns on the queen side and in the center, giving it a space advantage. Ethereal's eval started to increase on move 23 and it began to shuffle on the back rank, as if it was just waiting without any plan. Meanwhile KomodoMCTS created a 3 vs 1 pawn advantage and an advanced passer on the queen side. Ethereal gave a rook for a bishop, evals over 2. It took KomodoMCTS a while to convert the win, the game was adjudicated in a QRB vs QR position.


Stockfish - Komodo: See featured game below.

Ethereal - Andscacs: Ethereal had an eval advantage from the start, then it created a R vs BB imbalance and evals came down to 0. After exchanging queens evals became negative, Ethereal had a passer that got as far as the 6th rank and was stopped. The game reached a R vs BN position, Andscacs had a double passer on the queen side that Ethereal couldn't stop. First win for Andscacs in the division.

KomodoMCTS - Andscacs: Andscacs grabbed a pawn and allowed KomodoMCTS to develop a rook on the queen side. KomodoMCTS gave another pawn and created an advanced passer in the center, then regained the pawns and exposed the black king. Evals increased as KomodoMCTS attacked on the king side, Andscacs gave a rook for a bishop and the game reached a RRN vs RBN position. Andscacs had an advanced passer that was worth some material, but KomodoMCTS reduced to a winning tablebase 3P vs B position.

Houdini - KomodoMCTS: KomodoMCTS kept its king in the center. It allowed Houdini to open the king side as it captured a rook for a knight, and evals went over 1. The black king had to run to the queen side, it was still exposed and Houdini won back material. The engines reduced to a RBN vs RR position, the white pieces coordinated well to defend the king. The game was adjudicated when Houdini pushed a passer to the 6th rank.

Andscacs - Leela: The game reached a RBN vs QN position on move 26 with evals at 0. Leela pushed pawns on the king side and its eval became negative and jumped to 2. Then it gave two pawns on the king side and captured two pawns on the queen side, creating a passer there. After exchanging knights it took Leela a while but it found a way to convert.

Stockfish - Andscacs: Stockfish's eval was over 1 after a few moves in a wild opening. The game reached a QR vs QR position, at the right moment Stockfish exchanged queens and won a pawn. Then it exchanged rooks to get a winning king and pawns ending.


Featured game: Stockfish - Komodo
Premier division, round 16
Link to game on TCEC

The game started in a closed position, there were almost no exchanges in the first 20 moves and evals remained close to 0. On move 21 Stockfish locked the center with pawns, its eval increasing a little.


Most of the black pieces were on the queen side and Stockfish gradually moved its pieces to the king side. Stockfish's eval climbed higher as the tension grew, reaching over 4. When it was ready to attack Stockfish opened the king side with its pawns, but reacting to Komodo's moves it then won a bishop on the queen side instead.


The black king was still under threat along the open g file. Komodo kept its king surrounded by pieces and pawns, it made sure the king was safe but allowed Stockfish to push a pawn to the 7th rank.


The advanced passer cost Komodo a rook and the game.