Monday, May 2, 2022

Season 22 superfinal statistics

A summary statistics table of previous stages and seasons. 

Draw rate, wins
Final draw rate was 63%.

Game termination

The three most common game termination causes were:

53% - TCEC draw rule
30% - SyzygyTB
15% - Mate

There were no crashes in the stage.

Moves per game
Median= 71
Average= 74.4

There were 12 games longer than 100 moves, the longest was 194 moves (Stockfish - KomodoDragon, game 46, Stockfish won).

Time per game (hours) 
Median= 4:21
Average= 4:16

Openings

There were variable length book openings in this stage chosen by Jeroen Noomen and GM Matthew Sadler. The first letter of the ECO codes was distributed as follows:

The engines had almost no freedom to choose the opening variant, all the games repeated the same ECO and the same opening variant twice.

Reverse pairs, wins 

Reverse pairs, same moves 

Pairs of reverse games diverged much slower than usual, 20% diverged immediately out of book, 44% of the pairs diverged at most after 1 move. The longest repeated sequence of moves was 26 plys (KomodoDragon - Stockfish games 79 and 80, Sicilian dragon, Yugoslav attack, two white wins). Allowing transpositions the maximal repeat was 38 plys in games 97-98 (Sicilian, Richter-Rauzer, two draws).
 

Monday, April 25, 2022

Season 22 superfinal games 91-100, season summary

Stockfish is the winner of the season 22 superfinal. The final score is 28-9 with 63 draws. In the last 10 games there was no change in the +19 margin. There were 4 game pairs with two draws, in the final game pair KomodoDragon managed to win as white for the 9th time in the match, and Stockfish won the reverse game as it had done in the previous 8 times this happened. 

Stockfish was clearly better than KomodoDragon in the match, it took the lead right from the start and steadily increased the gap until the end. The remaining questions were whether Stockfish would break the highest gap record (it didn't, the record is +20 from season 12, also Stockfish - Komodo) and whether KomodoDragon would be able to win a game pair (failed with 9 wins, first TCEC that the winner does not lose a game pair). In the bookmaker competition of which lines led to a decisive game pair the final score was Jeroen Noomen (even pairs) 11 - 8 GM Matthew Sadler (odd pairs).

A total of 48 engines participated in season 22. The lower leagues were 1 DRR events with 12-14 engines and about one hour per game. Berserk started the season in the qualification league, and it was expected to advance since it had a good performance in the Swiss event of season 21. Indeed it had very good results in the qualification league and league 4 and it managed to advance twice. League 3 was a different story, first since the competition was harder, but also due to the promotion bottleneck. 

Several engines that played in higher leagues during season 21 did not participate in season 22 - Xiphos and AllieStein were the most prominent of these. As a result the season 21 relegation was disrupted and there were several weaker engines that started in higher leagues in season 22. From league 3 and on there were only 2 promotion spots per league and this created a bottleneck, judging by their strength there were more engines that "deserved" to promote than there were spots available. 

In league 3 Berserk was one of the 3 leaders but it only managed 3rd place behind Koivisto and Seer. Koivisto also performed well in the season 21 Swiss event and was expected to be a strong competitor, Seer was more of a surprise candidate. League 2 was a 2DRR event with 8 engines, Koivisto won the league convincingly. Seer couldn't repeat its success, it was in the leader group but only came 3rd behind Minic. League 1 was a 2DRR event with slightly longer games. Koivisto led from the start and it seemed to be heading to the premier division. However in the last RR it crashed once and lost two more games, and as a result it dropped to 3rd place behind rofChade and SlowChess. Another surprise was that Ethereal was only 5th in league 1, after appearing in the premier division every season since season 13 except once. 

The premier division was a 4DRR event with 2-hour games. From the start it was clear that Stockfish, KomodoDragon and Leela were in a competition for the superfinal, while the other 5 engines were only trying to avoid relegation. In 60 game pairs between the top3 and bottom5 engines the top3 engines won 48 and lost none. Within the top3 all the games were drawn except one game Stockfish won against KomodoDragon. However, of the 3 leaders it was Leela that failed to win game pairs against the weaker engines the most. It lagged behind the other two leaders and the gap slowly increased, in the end Leela was 3rd and 3 points behind 2nd place. Stockfish won the premier division and KomodoDragon was 0.5 points behind. This was quite an upset, Leela hadn't missed a superfinal since season 14 except once, and the last time KomodoDragon was in the superfinal (then just Komodo) was season 13.

This season there was a match between 3rd and 4th places of the premier division (infrafinal = infi), to determine 3rd place (??). Leela won the 50-game match against rofChade easily. After the superfinal another match is played between the winner of the infrafinal and the loser of the superfinal (subfinal = subfi). This match between Leela and KomodoDragon is still ongoing and it is less one sided, it appears Leela is going to win. I don't know if these events will return in the future, it looks like a way of compensating Leela fans for its absence in the superfinal, to show the world that it is still better than KomodoDragon.

There are many more events and bonuses planned for season 22, including a cup, a Swiss tournament, an FRC (chess 960) event. There is a 1-day per move event that already started, Stockfish and Leela play a game pair with time control of 12 hours per move. So far 1 move has been completed, the event will be resumed later and played in the background - not sure what that means. This is an intriguing and totally unwatchable event. We can also look forward to various bonus events (like VSOB - viewer submitted openings) before season 23 starts. 

A word about Cato (aka Nelson Hernandez). As I mentioned in the premier division report, Cato has retired from TCEC and will not provide opening books in the future as he had done since season 6 (!!). Cato is a TCEC icon, his database (Catobase) of chess games is legendary, he is one of the founding fathers of TCEC as we know it now. Cato's Fault is universal, and I can safely say that he is to blame that I am still watching and reporting about TCEC after so many seasons. His TCEC openings are a big part of why TCEC is a fun event to watch, and I always look forward to his chat appearances, either for chess or general knowledge or for a healthy smile.  

The Covid pandemic is still with us, two and a half years and 6 TCEC seasons so far. The situation is getting better though, the Omicron variant spread very fast but caused a less severe disease. In many countries there are less limitations on public gatherings and masks are no longer mandatory. It is not over yet but there is hope that life can return to a more normal mode. 

During this season Russia invaded Ukraine and war broke out, it is still going on 2 months later. The destruction and human suffering is enormous, many lives have been lost in battle, millions have fled their homes and are refugees in their country and outside in neighboring countries. I have no illusion that there can be a happy end to this conflict, but I do hope there is an end and soon. 

That's it for me this season, hope to be here for the next one.

Go TCEC!!

================================

Games 91-92 started with a 12-ply book in the Caro Kann, Bronstein-Larsen variation, played in many high level human games 30-40 years ago. Game 91 left theory very quickly. There were no pawn exchanges after the start. The engines exchanged a pair of bishops, other than that they played quiet moves mostly behind the pawn lines. Evals came slowly down, on move 43 there was a short series of exchanges that left a RRB vs RRN position. Evals were low enough for the draw rule. In game 92 the engines followed human theory for a few moves, they followed a PV agreement and exchanged queens. Stockfish moved its king forward without castling and KomodoDragon castled long. There were many pawn moves, Stockfish created a passer in the center and a pawn exchange opened a central file. Evals came down, another pawn exchange opened a file on the queen side while Stockfish created a passer on the king side. Stockfish gave a pawn and moved a rook forward, this gave KomodoDragon a passer that moved to the 2nd rank. All the threats canceled out, a series of exchanges reduced to a RB vs R position with KomodoDragon 2 pawns up, the game was quickly adjudicated.

Games 93-94 started with an 8-ply book in the Alekhine's defense, modern Schmid variation, that was played in a Carlsen - Nakamura game. In game 93 after the pieces were developed there were a few exchanges, then KomodoDragon gave a rook for a bishop and weakened the black pawn structure. The engines cleared the queen side pawns, KomodoDragon went a pawn up and created a passer. Evals came down to 0, KomodoDragon pushed the passer forward and eventually regained material. The game reached a QB vs QB ending and was adjudicated. In game 94 the engines opened a file in the center, then played a PV agreement where a pair of rooks was exchanged and Stockfish went a pawn up. Stockfish gave two pawns and created a queen side passer, after exchanging queens the passer moved to the 7th rank. In a RBN vs RBB position evals came slowly down, KomodoDragon blocked the white passer and the engines exchanged pawns on the king side. The game was adjudicated after a minor piece exchange.

Games 95-96 started with an 11-ply book in the Vienna Mengarini variation, with an advantage for black. In both games black captured a pawn and forced the white king to move. In game 95 Stockfish traded both its bishops for knights, and its king didn't castle as well. The engines exchanged queens and (negative) evals came down. The exchanges continued, the game was adjudicated in a RB vs RN position. In game 96 KomodoDragon castled short and gave the pawn back. The engines exchanged pieces and only QRB vs QRB remained on move 26. The engines mostly shuffled and (negative) evals came down, eventually the game reached a same color bishop ending. KomodoDragon was a pawn up and its eval was too high for the draw rule, the game was adjudicated 40 moves later.

Games 97-98 started with a 24-ply book in the Sicilian Richter-Rauzer variation that appeared in a Mikhail Tal game from 1973. One pair of pawns and one pair of knights were exchanged, the engines castled in opposite directions. The games then repeated another 40 plys, at the end of which only rooks and bishops remained on the board, evals were around 0.5. In game 97 evals dropped to 0 after some shuffling, the engines continued to exchange pieces and pawns and the game was adjudicated in a king and pawns endgame. In game 98 the engines quickly reduced to a drawn rook ending and the game was adjudicated.

Games 99-100 started with a 16-ply book in the Sicilian Scheveningen, Tal variation, played in high level human games. In both games white castled long immediately after book, the opposite direction of the black castling. In game 99 KomodoDragon pushed pawns on the king side and Stockfish pushed pawns on the queen side. Evals started to increase after a pawn exchange on the king side, KomodoDragon attacked the black king. Stockfish avoided mate and exchanged pieces, the game reached a RBB vs RBB position with white a pawn up.

The engines continued to trade pawns and exchanged a pair of bishops. KomodoDragon had two connected passers on the queen side, much stronger than the passer Stockfish had on the king side. Stockfish lost the bishop for a passer and the game ended in a tablebase win.

In game 100 the pawns mostly stayed back, the engines opened the center and exchanged pieces. Queens were off early, by move 27 only RRB vs RRB remained. Evals were around 1.5, Stockfish had a passer that KomodoDragon covered with its rooks, other than that the advantage wasn't obvious. However Stockfish's eval slowly increased, and on move 31 both evals jumped.


Evals continued to increase though not a lot seemed to be happening on the board. The engines stabilized the king side pawns, then the white king moved to the center where it could support the isolated e pawn and free a piece. KomodoDragon decided not to wait and exchanged pawns on the queen side, creating a black passer and two connected white passers. Stockfish changed plans and moved its king back to block the black passer, then it moved a rook forward. After some shuffling the engines exchanged a pair of rooks. 

The engines reduced to a rook ending and predicted mate in their PVs. KomodoDragon lost a rook for a passer, it was able to queen a pawn but too late to stop mate. There were two white wins in this game pair, the score is 28-9.


Saturday, April 23, 2022

Season 22 superfinal games 81-90

After 90 games Stockfish leads 27-8 with 55 draws. Stockfish adds another 2 game pair wins, it had a lead of +19 with 5 game pairs to play. KomodoDragon still hasn't won a game pair, in these 5 game pairs it hasn't won a game with white, something it managed to do at least once in each 5 game pair group in games 1-80.

Games 81-82 started with a 20-ply book in the Nimzo-Indian Rubinstein variation, played by GM Sadler (the second time I've seen this in this match). White started with a pawn majority on the queen side. In both games the engines castled short after the start. In game 81 a pawn exchange on the queen side created a passer for KomodoDragon. After some preparations there was a series of exchanges that left a QB vs QB position, KomodoDragon was up a pawn with two passers. However after exchanging queens the game reached an opposite color bishop ending, evals came down and the game was adjudicated. In game 82 the pawn exchange on the queen side created passers for both engines. Stockfish captured a pawn with its queen on the king side, then KomodoDragon gave another pawn and exchanged queens. In a series of exchanges KomodoDragon got one of the pawns back and the game reached a RN vs RB position. KomodoDragon wouldn't lower its eval for the draw rule, the engines shuffled for a long time. The game was adjudicated after the rooks were exchanged.

Games 83-84 started with an 18-ply book in the King's Indian, normal variation, with a locked center and without exchanges. In game 83 KomodoDragon castled long, the engines pushed pawns and locked the king side, and then they locked the queen side as well. On move 25 there was only one possible pawn move left, the board was totally blocked. Stockfish's eval came down, KomodoDragon was still hopeful. The last pawn move and a bishop exchange extended the shuffle to move 105, the game was adjudicated close to a 50-move draw. 

In game 84 Stockfish castled long as well, the engines locked the g and h files but a pawn exchange kept the f file partially open. There was a minor piece exchange on the queen side and the black a pawn became isolated. There was a period of shuffling with evals around 2, then evals increased while Stockfish moved a knight b5-c3-e2-g3, preparing for an attack on the king side.


KomodoDragon didn't wait and it exchanged the f4 bishop for a knight. While defending the f file KomodoDragon abandoned the a pawn, Stockfish now had a queen side passer. Stockfish decided to shift to the queen side, and first it moved its king from a2 all the way to g2. The engines exchanged queens and KomodoDragon captured two pawns on the queen side, but the white a pawn started to move supported by a rook. 

KomodoDragon had to give a knight to capture the passer, Stockfish was a rook up for pawns and it saw mate in its PV. Stockfish moved a rook forward, the black pawns had no defense. Stockfish created a passer and won. Stockfish wins the game pair, it leads 26-8.

Games 85-86 started with a 14-ply book in the French Winawer advance, poisoned pawn variation, played at the highest level of human chess. Both games diverged quickly from theory. In game 85 after a few early exchanges the engines played out a long PV agreement and reduced to a QRR vs QRR position on move 26. Evals came down to 0, captures and pawn moves kept the game going for 40 more moves. In game 86 the queens were off early, KomodoDragon pushed pawns on the king side and evals came slowly down. There were many pawn exchanges, the engines exchanged a pair of rooks through an open file on the queen side, then reduced to a drawn N vs B ending.

In game 87 KomodoDragon was ahead on development after the start, evals were over 1 but did not increase. Stockfish pushed a pawn on the queen side and opened a file, for several moves it offered a knight and KomodoDragon didn't accept - there was either a pin or another a more dangerous threat to deal with first. After the knight moved the engines opened the center, then gradually exchanged pieces until the game reached a rook ending. KomodoDragon was a pawn up but only enough for a draw. In game 88 KomodoDragon did not develop any piece on the queen side after the start. For a few moves it seemed Stockfish's eval may start to increase but it stayed mostly under 1.5. The engines exchanged minor pieces, then the queens were off. KomodoDragon's pawn structure was weak but evals went below 1 and it stabilized its position. The engines again reduced to a drawn rook ending

In game 89 the engines opened the center, evals stayed around 1 until the engines exchanged most minor pieces. By move 27 only QRR vs QRR were left, both engines had a passer in the center. There were a few pawn trades and evals came down until the game was adjudicated.

In game 90 there were no pawn exchanges after the start and the center stayed closed. A minor piece exchange resulted in a white passer in the center. KomodoDragon pushed pawns on the king side, it formed a long line across the board that looked impossible to penetrate. The engines shuffled, on move 44 the last knights were exchanged, no piece could jump across the line. The shuffle continued and the engines went into blitz mode. Stockfish's eval started to increase as it contemplated what would happen if it sacrificed its bishop to break the wall. 


KomodoDragon protected d5 and Stockfish sacrificed the bishop on a5 and captured two pawns. Stockfish had connected passers in the center, KomodoDragon decided to counter by giving two pawns on the king side and moving its queen forward to attack the white king. The engines traded a pair of rooks, KomodoDragon captured another rook for a bishop but then it lost a rook to stop one passer. This left a queen ending, Stockfish up two pawns and with a passer on the 6th rank. 

KomodoDragon could capture pawns but it had to stop the passer first. With checks KomodoDragon managed to capture the passer on d6, Stockfish responded by capturing the black a pawn. It was a long endgame but there was no doubt Stockfish would covert. Eventually Stockfish queened a pawn and won with two queens against one. Stockfish wins the game pair, it leads 27-8.


Thursday, April 21, 2022

Season 22 superfinal games 71-80

After 80 games Stockfish leads 25-8 with 47 draws. Stockfish won two more game pairs, with 20 games and a +17 lead it is very close to win the match formally. Of course there is no doubt it is going to win. KomodoDragon won another game and lost the reverse, the 8th time in this match. Curious that there has been one game pair with two white wins in each report I wrote so far this match, two more to go.

In game 71 KomodoDragon castled long and Stockfish kept its king uncastled in the center. The engines played out a long PV, KomdoDragon went a pawn up and opened a file in the center. The game reached a QBN vs QBN position, evals were around 1.5. However, evals dropped after the bishops were exchanged, Stockfish moved its pieces forward and threatened the white king. The white knight helped defend the king and KomodoDragon gave checks with its queen until the game was adjudicated. 

In game 72 again Stockfish castled long and KomodoDragon kept its king uncastled in the center. This time Stockfish pushed pawns on the king side and didn't open the center. There was a long PV agreement in which the engines opened the queen side and exchanged many pieces. The game reached a RBN vs RBN position on move 24, with white a pawn up and a passer on the queen side.


The engines exchanged pawns and opened the position, the black rook developed through the h file. KomodoDragon's main concern was the white passer, it decided to give its knight to capture the passer and another pawn. This left Stockfish with one last pawn, all the pieces on the board moved either to attack this pawn or defend it.

This 9-man position was easy enough for this level of engine play, not sure how easy it is for humans. KomodoDragon couldn't afford to lose a piece for the last white pawn. Stockfish captured the black pawn quickly, it took a while but eventually Stockfish managed to capture a piece anyway using a discovered check. The game ended in a tablebase win after that. Stockfish wins the game pair, it leads 23-7.

In game 73 there were a few minor piece exchanges and one pawn exchange after the start. Evals came down and the engines started to shuffle on move 32. KomodoDragon's eval was too high for the draw rule, On move 74 KomodoDragon's eval dropped to 0 and then the exchanges started. The game was adjudicated 30 moves late in a RR vs RN position. In game 74 there were many early exchanges, only RBN vs RBN remained on move 20. Evals came down gradually, the engines exchanged pawns and bishops and the game was adjudicated by move 47.

Games 75-76 started with an 18-ply book in the French Winawer, Petrosian variation. The center was blocked and in both games black castled long. In game 75 Stockfish moved a knight forward on the queen side. KomodoDragon gave a pawn and created a passer on the queen side, after castling long it traded a rook for the black forward knight. The exchanges continued until only BBN vs RBN remained, KomodoDragon was a pawn up with two passers. Evals were 0 and the game was adjudicated by the draw rule. 

In game 76 KomodoDragon pushed pawns on the king side, Stockfish didn't think this was a good plan and its eval increased. KomodoDragon opened the g file, there seemed to be no safe direction for the white king to castle. However Stockfish wasn't worried, and at the end of a PV agreement on move 24 KomodoDragon's eval jumped, it acknowledged it had a problem.


Stockfish pushed the h pawn, the white king was safe in the center. After exchanging a pair of rooks the white king walked to the h file and moved its queen side rook to the open g file. KomodoDragon kept its pieces on the queen side to protect its king from the coming invasion, Stockfish captured the h pawn and created a passer. 

KomodoDragon tried to counter on the queen side and created a passer there, but it lost a rook for the white h pawn. The game continued for 25 more moves but with a rook advantage the outcome was obvious. Stockfish wins the game pair, it leads 24-7.

In game 77 the evals were relatively low after book, the engines locked the center and exchanged a few minor pieces. KomodoDragon castled long and Stockfish pushed pawns on the queen side. The engines opened a file on the king side and then reduced to a bishop ending with low evals. KomodoDragon created a passer and wouldn't lower its eval for the draw rule. The game was adjudicated after 25 shuffling moves. In game 78 Stockfish also castled long, this time it pushed pawns on the king side. The engines played out a long PV agreement, KomodoDragon went up a pawn and it had two passers in the center still close to their initial square. Stockfish placed a knight on e6 and blocked the passers, both kings were vulnerable. KomodoDragon threatened mate on the queen side, then gave a knight for a pawn on the king side. Stockish gave the material back and attacked the black king, however evals were low and the game was soon adjudicated.

Games 79-80 started with a 16-ply book in the Sicilian Dragon, Yugoslav attack variation, still in theory of high level human chess. The games then repeated 26 more plys where the engines castled in opposite directions, black gave a pawn and opened the queen side, white captured a rook for a bishop and black regained the pawn. All the black pawns were on the king side, white had two passers on the queen side. 


In game 79  KomodoDragon exchanged bishop for knight, Stockfish's eval came down for a while but it then came back up. KomodoDragon pushed the a pawn forward, eventually Stockfish gave a knight to get rid of it. KomodoDragon was then up a rook for pawns, the engines traded a pair of rooks and reached a QRN vs QB position.

Stockfish was 3 pawns up and the white king was exposed, however that was not enough to compensate for a rook. The engines traded pawns until there were no white pawns left, the white king started to move forward protected by pieces. Stockfish exchanged queens and the game soon ended in a tablebase win. 

Stockfish had a different approach in game 80, it kept the queen side pawns as they are and traded both its pawns on the king side. Then it exchanged pieces and gave back the material so that it was only a pawn up in a QRB vs QRB position. 

Both engines were sure Stockfish was going to win, though the material advantage was small and indeed the black pawns had a head start. KomodoDragon made no effort to push its pawns, it was busy avoiding an exchange of pieces. Perhaps the black king was vulnerable without pawn support. After a while the engines exchanged queens, and Stockfish pushed its pawns. KomodoDragon blocked the white pawns but eventually lost the rook and the game. There were two white wins in this game pair, Stockfish leads 25-8.


Tuesday, April 19, 2022

Season 22 superfinal games 61-70

After 70 games Stockfish leads 22-7 with 41 draws. Stockfish won two more game pairs, KomodoDragon again couldn't hold as black and win its first game pair in its 7th attempt. 

Games 61-62 started with a Modern Averbach system variation, in both games the black king was forced to move early. In game 61 there were no pawn exchanges, evals were under 1 and remained constant as the engines exchanged minor pieces. KomodoDragon castled long but did not try to open the position, the engines shuffled for a long time. KomodoDragon avoided the 50-move draw and then the exchanges started and evals dropped to 0. The game was adjudicated in a RN vs RB position. In game 62 KomodoDragon gave an early pawn on the queen side, a minor piece exchange opened  afile in the center and the engines exchanged queens. Stockfish castled long while KomodoDragon walked with its king to the king side. Evals came down and in after a series of exchanges only RR vs RN remained. The white rooks came forward and captured two pawns, KomodoDragon attacked the white king. Stockfish avoided a perpetual check but lost a rook for a knight, the rook ending was a draw.

In game 63 there were no exchanges after book, the engines moved their pieces on the crowded board either preparing an attack or defending against something. Evals were around 1.5 and didn't change a lot. On move 26 KomodoDragon locked the center, and there was an exchange of knights. Stockfish tried to close the king side and KomodoDragon exchanged a pair of pawns to create a small opening. There was a period of shuffling, both engines moved their kings away from the king side, the white king walked all the way to the opposite corner. KomodoDragon's eval started to increase and on move 52 the eval jumped, KomodoDragon pushed the f pawn and was ready to open the position.


Stockfish was on increments and may have missed something, this move caught it by surprise and its eval jumped as well. KomodoDragon gave two pawns and broke through the center. The white major pieces moved to the center and the black king was in danger, the black pieces could only watch from the side. KomodoDragon then offered a rook in the center. 

Stockfish refused to take, exposing the king would lead to more trouble. Instead it gave two pieces and its queen tried to give checks. This only lasted for a short while, the material advantage was too great and the game ended in mate.

In game 64 again there were no exchanges after the start. Stockfish locked the center earlier and the white king stayed uncastled in the center. On move 23 a pair of pawns was exchanged on the king side, evals increased a little as Stockfish moved pieces there and threatened the black king. On move 38 another pawn exchange opened two files on the king side. The white king walked to the queen side, evals jumped when a file opened there and Stockfish took control of it after exchanging a pair of rooks.


KomodoDragon infiltrated through the king side, for a while Stockfish played defensively though evals continued to increase. Nothing came out of KomodoDragon's attack, on move 62 Stockfish went a pawn up.

Stockfish increased the pressure on the back ranks, eventually KomodoDragon exchanged pieces and was a piece down in a RBN vs RN position. Stockfish had too many advancing passers, KomodoDragon lost more material and the game ended in mate. There were two white wins in this game pair, Stockfish leads 20-7.

In game 65 the engines opened the center, and KomodoDragon created a central passer through exchanges. Stockfish developed its queen side pieces late, it managed to capture the passer and was a pawn up. A series of exchanged left a QRN vs QRN position, KomodoDragon moved a rook forward and regained the pawn. KomodoDragon had a pawn majority on the queen side, it even captured another pawn and created a passer. However evals dropped, the engines reduced to a queen ending and the game ended in a tablebase draw.

In game 66 again the engines opened the center, this time Stockfish gave a pawn and its queen came forward to create a central passer. On move 13 the engines entered a very long PV agreement, the queens were exchanged and KomodoDragon captured the passer. KomodoDragon captured pawns but lost a piece, evals started to increase and at the end of the PV agreement the game reached a BNN vs BN position with black 2 pawns up.

The engines traded pawns until there was only one white pawn and two black ones. Stockfish kept its king on the king side to keep an eye on the black passer, KomodoDragon moved its king to the center as an additional defender while the white pieces tried to use their numerical advantage. It took time to move the knights to the right squares and drive away the black king, eventually Stockfish was ready to capture the black pawn on the queen side.

Stockfish changed its mind in response to KomodoDragon's moves, instead of capturing the pawn it exchanged knights and cleared a path for its last pawn. KomodoDragon couldn't stop the passer without losing its bishop, eventually Stockfish queened and ended the game in mate. Stockfish wins the game pair, it leads 21-7.

In game 67 both engines castled long, there were a few minor piece exchanges and one pawn exchange that weakened the white pawn structure. Evals stayed around 1 and the engines mostly shuffled, the white king walked back to the center. On move 37 Stockfish opened the king side and created a passer. When KomodoDragon exchanged pawns on the queen side Stockfish's eval dropped, a series of exchanges reduced to a RR vs RB position. KomodoDragon thought it had an advantage but with one rook blocking the black passer it couldn't improve and just shuffled. Both evals dropped, after 30 moves the exchanges started. There was a pawn race and both engines queened, however the game ended in a tablebase draw.

In game 68 there were a few pawn exchanges in the center and the engines opened the c file. Stockfish kept its king uncastled in the center while KomodoDragon castled short. On move 24 the first pieces were exchanged and the engines started a long PV agreement. Evals increased after Stockfish placed a strong knight on d6 forking queen and rook. KomodoDragon escaped the fork but the knight restricted its movement. KomodoDragon grabbed a pawn on the queen side, it realized it was in trouble despite the small material advantage.

KomodoDragon gave back the pawn to open a diagonal for its LS bishop. The white king was exposed, the black queen moved forward and Stockfish exchanged queens. KomodoDragon was reluctant to exchanged the white knight since that would create an advanced passer for white. However after a while KomodoDragon did exchanged a bishop for the knight and then gave a rook for a bishop to capture the passer. 

The material advantage was small but KomodoDragon couldn't hold this position. Stockfish managed to capture the pawns on the queen side, then mate threats forced KomodoDragon to give pieces, game over. Stockfish wins the game pair, it leads 22-7.

Games 69-70 started with a 32-ply book in a closed Ruy Lopez, Flohr system, a line played at the top level of human chess. In game 69 there were only a few pawn moves after book, the position remained closed. There were a few minor piece exchanges and evals came down. The game was adjudicated while most pieces and pawns were still on the board. In game 70 KomodoDragon pushed pawns on the queen side, it gave a pawn and both engines created a passer. Stockfish gave a rook for a bishop, after a few exchanges KomodoDragon gave the material back. Evals came slowly down and the game reached a QRN vs QRN position. After exchanging queens evals were low enough for the draw rule.


Monday, April 18, 2022

Season 22 superfinal games 51-60

 After 60 games Stockfish leads 19-6 with 35 draws. KomodoDragon still hasn't won a game pair, it won its 6th game and Stockfish won the reverse again. Stockfish only won 1 game pair out of the last 5, it has a +13 lead with 20 game pairs to go. The highest win margin for a TCEC superfinal with 100 games is +20, this record may be broken this season. 

Games 51-52 started with a 20-ply book in the Dutch Leningrad variation. In game 51 the engines left theory quickly, Stockfish pushed pawns in the center and managed to get a pawn to f2 through an exchange. In a long series of exchanges the engines reduced to a QRB vs QRB position with white a pawn up. After some shuffling the queens were exchanged, evals came down and the game was adjudicated. In game 52 again the engines left theory but in a different line, again Stockfish was a pawn up. Stockfish pushed a passer in the center to the 6th rank, a second passer was blocked by the black queen. Evals came down and the game was adjudicated still with many pieces on the board. 

Games 53-54 started with a 12-ply book in a KID normal variation, which was played in one of GM Sadler's games (coinicidence?). In game 53 there were a few pawn exchanges after the start, all pieces stayed on the board. KomodoDragon pushed a pawn to h6, forcing a black bishop to the corner. The first piece exchange was on move 26 when the engines exchanged bishops. Stockfish managed to get its bishop out of the corner, it was later exchanged for a knight. Evals came down, the engines exchanged pieces until reaching a drawn rook endgame. In game 54 again there were a few pawn exchanges after the start. Stockfish pushed the h pawn but exchanged it rather than move it to h6. There was one B for N trade and evals came down. In a series of exchanges the engines reduced to a QR vs QB position, KomodoDragon ended the game in a perpetual check.

Games 55-56 started with a 2-ply book, 1 d5 b5, the Polish defense. In game 55 both engines did not castle their kings. KomodoDragon let its king side rook out through the h file and the white king walked to safety. Stockfish moved its king to the 7th rank to clear a path for its king side rook. There were a few pawn and minor piece exchanges, Stockfish blocked the queen side with its knights but it had two weak pawns there. Evals increased slowly, the engines exchanged queens and Stockfish tried to block across the board.


For a while the engines shuffled while KomodoDragon decided where to attack. On move 43 KomodoDragon started to attack on the queen side, it reduced to a RN vs RN position a pawn up. Pawn trades opened the board, both engines had passers and KomodoDragon had a pawn majority and connected pawns on the queen side.

KomodoDragon captured the black a pawn to create connected passers. It gave away its f passer and then gave the rook for a knight. Stockfish could not stop the two passers advancing with its rook alone, the game ended in a tablebase win.

In game 56 Stockfish castled its king, then made the black king move through an exchange. KomodoDragon moved its king to h7 so its king side rook could get out of the corner. In a long PV agreement KomodoDragon gave two pawns to open the board and activate its pieces. The engines continued to exchange pieces until only RB vs RB were left.


Stockfish had to be careful not to get into an opposite color bishops ending, so it was cautious and patient. After exchanging a pair of pawns on the king side Stockfish found an opportunity to push the e pawn forward to the 7th rank. KomodoDragon guarded the queening square, but also had to protect its other pawns. KomodoDragon refused to give away its a pawn, in the end Stockfish traded its passer for the black g pawn. 

It was still very hard for Stockfish to push the g pawn forward safely. It used the threat of a rook exchange that would create an advanced passer on the queen side to drive the black rook away. On move 70 the white g pawn advanced, and 10 moves later KomodoDragon was forced to give its bishop for the passer. The last black pawn was captured and the game ended in a tablebase win. There were two white wins in this opening, Stockfish leads 18-6.

Games 57-58 started with an 18-ply book in the Ruy Lopez anti Marshall variation. In game 57 KomodoDragon went up  a pawn early and evals came down quickly. After move 20 the engines exchanged pieces and the game reached a RB vs RB position. KomodoDragon wouldn't lower its eval for the draw rule, this delayed adjudication by 30 moves. In game 58 Stockfish went a pawn up in a different line. KomodoDragon regained the pawn, evals came down as the engines exchanged pieces. The game reached a QR vs QR position and Stockfish went a pawn up again. Here adjudication was delayed for 40 moves because of exchanges and pawn moves. 

Games 59-60 started with a 16-ply book in the KID orthodox variation, a line played many times in high level human games. In game 59 the engines left theory quickly, the center was blocked and there was one pair of pawns exchanged that opened a file on the queen side. The engines mostly shuffled, a pair of bishops were exchanged on move 25, a pair of rooks on move 35. On move 57 the remaining bishops were exchanged and there was a long shuffle, 30 moves later the engines exchanged pawns, evals came down and the game was adjudicated.

In  game 60 the engines left theory as well. KomodoDragon surprised Stockfish with its 11th move, and Stockfish's eval jumped after black's 12th move. KomodoDragon predicted the moves correctly in its 11th move PV, but Stockfish considered the line a mistake. The center opened, the white queen came forward and Stockfish captured two pawns. After exchanging queens the engines traded NN for R, the game reached a RR vs RNN position on move 28. KomodoDragon's eval also increased, too late to change its choice.


The engines were still in PV agreement. Stockfish had a passer but was down a piece and it was difficult to support the passer. KomodoDragon captured the b pawn, Stockfish pushed the e pawn forward. This was also a danger to the black king, eventually KomodoDragon captured the e pawn while Stockfish captured the black a pawn. 

The flank passer was a greater challenge for the black knights, while KomodoDragon was busy watching the passer Stockfish cleared the black pawns on the king side and created connected passers there. Stockfish used a timely rook for knight sacrifice to queen a pawn and win. Stockfish wins the game pair, it leads 19-6.


Friday, April 15, 2022

Season 22 superfinal games 41-50

 After 50 games Stockfish leads 17-5 with 28 draws. Stockfish won two more game pairs, though one of them was a result of a blunder KomodoDragon made after a long shuffle and while playing on increments. KomodoDragon won a game and for the 5th time lost the consecutive reverse game. Stockfish's lead is +12 at the half way point of the match, it is almost certainly going to win. What remains to be seen is the final margin and whether KomodoDragon will be able to win a game pair.

In game 41 Stockfish managed to lock the center with diagonal pawn lines. after exchanging a few minor pieces the engines started to shuffle. There was one pawn exchange on the queen side and a few pawn moves on the king side, other than that only shuffling until move 68. KomodoDragon pushed a pawn on the king side and this led to exchanges and simplification. Evals were 0 and the game was adjudicated a few moves afterwards. In game 42 the engines exchanged a pair of pawns on the queen side early. After both engines fully developed their pieces Stockfish opened the queen side completely and went a pawn up. There were many exchanges and the game reached a QRN vs QRB position. Stockfish had a passer but couldn't support its moving forward. KomodoDragon regained the pawn on the king side, after exchanging queens evals came down. The game was adjudicated after the pawns stopped moving.

Games 43-44 started with an 18-ply book in the French Steinitz Boleslavsky variation, played at the highest level in human matches. Both games continued in a PV agreement for 9 more plys, black gave a knight for two pawns and created a passer on the queen side. In game 43 Stockfish pushed its passer to the 3rd rank, it was supported by another pawn and by the queen that moved forward on the queen side. KomodoDragon gave a pawn on the king side, most of its pieces were ready to defend against the black passer advancing while its queen moved forward on the king side. The black king ran to the queen side and the white queen captured a pawn.


The white queen was almost trapped, KomodoDragon found a safe square for it on h4. Stockfish gave another pawn on the king side and tried to threaten the white king with its major pieces. KomodoDragon protected its king and shifted to the queen side, it gave a rook for a knight to break up the black pawns. Now there were two black passers on the queen side, both isolated. 

KomodoDragon captured the two passers quickly, Stockfish had no other threats. The material difference was small but sufficient, KomodoDragon exchanged bishops then created a passer in the center. Stockfish lost material and the game ended in mate.

In game 44 both engines castled short, KomodoDragon pushed the passer to the 3rd rank as before. In a long PV agreement Stockfish gave a rook for a knight and captured the passer, then the engines reduced to a BNN vs RB position on move 30.


Evals were over 2 though this didn't look like an easy win. KomodoDragon tried to find safe spots for its pieces and enough protection for its pawns. The black bishop moved in front of the pawns in the center. The engines traded pawns until there were only 3 left for each engine, mostly in the center. 

Stockfish exchanged bishops and KomodoDragon could not protect the black pawns with its king alone. Stockfish captured two pawns and queened a passer to win. There were two white wins in this game pair, Stockfish leads 15-5.

Games 45-46 started with a Caro Kann advance variation in a line played at the highest level of human chess, with a blocked center. In game 45 the engines opened the c file and eventually Stockfish castled short. All the queen side pawns were exchanged except for one, KomodoDragon went a pawn up with a passer still on the 2nd rank. Stockfish managed to capture the passer, it fortified the king side with pieces surrounding its king. KomodoDragon opened the king side with a knight for pawns sacrifice, then after a series of exchanges the game reached a QB vs RBB position. Evals came down, both engines did not attempt to attack and the game was adjudicated.

In game 46 there was an early pawn exchange on the queen side but the files remained closed. The engines exchanged a few minor pieces, again KomodoDragon castled short and the engines started to shuffle. A few pawn moves and the exchange of the remaining knights extended the game beyond move 100. The engines were low on time and in blitz mode. A pawn exchange on the king side created an opening that the black queen guarded. On move 120 Stockfish gave a pawn and opened the h file. KomodoDragon moved its queen forward but couldn't force an exchange. Suddenly Stockfish's eval jumped, KomodoDragon noticed too late that its queen walked into a trap.


Stockfish threatened Re1 and capturing the queen, KomodoDragon gave a pawn to free its queen and this opened another file on the king side. KomodoDragon managed to exchange queens but not before Stockfish captured another pawn. The game reached a RB vs RB position with white a pawn up.

Stockfish had two passers, KomodoDragon lost another pawn and couldn't prevent a queening for long.  Stockfish wins the game pair, it leads 16-5.

Games 47-48 started with a 16-ply book in the King's Indian, Saemisch orthodox variant, played in the Karpov-Kasparov match in 1990. In game 47 there was one pawn exchange and several minor piece exchanges after the start. By move 26 all the knights were gone and the engines started to shuffle. After 20 moves the engines exchanged pawns on the king side and resumed shuffling. On move 70 KomodoDragon gave a pawn on the queen side, and a few moves later the queen side opened. A series of exchanges reduced to a rook ending, evals were 0 and the game was adjudicated.

In game 48 KomodoDragon traded its queen for two bishops and two pawns right after book. There were no exchanges after that, it took KomodoDragon a while to develop its queen side. Evals increased while Stockfish pushed pawns forward and created a space advantage. KomodoDragon had many pieces but their movement was restricted by its own pawns. Stockfish threatened the backward c pawn and forced KomodoDragon to exchange knights, this created a small opening on the queen side. 


For a few moves Stockfish offered a knight on f5 but KomodoDragon wouldn't take, opening the king side was probably dangerous for its king. Instead KomodoDragon exchanged a bishop for the knight. After some preparation Stockfish attacked the queen side, it cleared the pawns and moved both rooks forward. 

Stockfish had too much fire power for KomodoDragon to handle. After exchanging a pair of rooks Stockfish captured a piece, the game ended in a tablebase win. Stockfish wins the game pair, it leads 17-5.

Games 49-50 started with an 10-ply book in the Ruy Lopez Schliemann defense, then repeated the next 36 plys in PV agreements and a few transpositions. The engines castled in opposite directions and both had a central passer. In game 49 the engines exchanged queens quickly, evals dropped to 0 as the exchanges continued. Both passers were captured and the game reached a RB vs RB position. The game ended in a repetition of checks. In game 50 the queens were exchanged as well, but the passers stayed on the board longer. However both engines could not push the passers forward, eventually they were captured and the game reached a drawn rook ending.