Stockfish is the winner of the season 23 superfinal. The final score is 27-10 with 63 draws. In the last 10 games Stockfish won two more game pairs and increased its lead to 17. There were two game pairs with two white wins (for a while it seemed Leela would hold in one of these), and one with two draws despite the high bias of the openings. Curiously, this was the same result as the first 10 games.
Stockfish was in the lead from the beginning of the match. Leela won a game pair in the 7th opening played, this was the first loss for Stockfish in this season. In the superfinal of season 22 Stockfish didn't lose a single game pair to KomodoDragon, and there was hope this season the superfinal would be more competitive. However, in the following 24 game pairs Stockfish didn't lose a single game and won 9, it was leading by 10 after game 66. Leela managed to win a second game pair but it clearly didn't have a chance of winning the match. The final lead of 17 is only 2 less than the lead Stockfish had in the previous superfinal against KomodoDragon.
In the bookmaker competition of which lines led to a decisive game pair the final score was Jeroen Noomen (even pairs) 11 - 10 GM Matthew Sadler (odd pairs). This competition was very close, it was decided only in the last game pair played.
A total of 40 engines participated in season 23. There were a few changes in the league format of season 23. Leagues 3 and 4 were cancelled, instead there was larger qualification league with 18 engines playing a 9 double round swiss tournament. Four engines advanced from qualification to league 2 and from league 2 to league 1, both leagues with 12 engines playing 2 DRRs. The engine placement in the leagues was determined not by the results of the season 22 leagues but by the result of the swiss tournament - probably a way to allow stronger engines to start with a higher rank so they can get to the higher leagues faster.
Some of the races in the lower leagues were close and interesting, but overall there were no really exciting events. Most of the engines that advanced from a lower league were later ranked at the bottom of the higher league, none managed to advance twice. In league 1 Koivisto performed worse than was expected by its previous results, reports in the chat claimed that the version submitted had a bug that made it weaker. The two engines that advanced to the premier division were Ethereal and Berserk.
In the premier division there was a clear divide between the top 3 engines, Stockfish, Leela and KomodoDragon, and the rest of the field. The top3 engines won almost all the game pairs against the bottom5 without loss. Within the top3 Stockfish beat KomodoDragon in all their 4 game pairs, and it also beat Leela once. As a result Stockfish led the division from the start and finished first. The second superfinal spot was a race between Leela ans KomodoDragon that was only decided in the last round in a tiebreak. In the game pairs between them both Leela and KomodoDragon had one win, KomodoDragon had a better performance against lower ranking engines but Leela had a better result against Stockfish and that was the deciding factor.
There was a match between KomodoDragon and Ethereal (3rd and 4th in the premier division), as expected KomodoDragon won easily. Ethereal improved its performance significantly in season 23, 4th place in the premier division is its best result in TCEC. However, it is still no match for the top3 engines. Another match beween Leela and KomodoDragon in ongoing, and this is much closer. So far KomodoDragon has a small lead.
TCEC continues to run various other events, a cup, a Swiss tournament, FRC (Chess 960), DFRC (960x960), and more bonus events. The 1day/move games have diverged, looking at the evals the best guess is that both will be wins for white.
The world continues to go round outside of TCEC. The chess world was shaken when the reigning world champion Magnus Carlsen accused Hans Niemann of cheating, after losing a game. Covid is still a thing, but it is getting a lot less attention - I'm concerned about the northern hemisphere winter and about whether China can prevent an outbreak. Russia is still fighting in the Ukraine with no end in sight after 9 months. The football world cup has just begun in Qatar.
That's it for me this season, hope to be here for the next one.
Go TCEC!!
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Games 91-92 started in the Sicilian, Nimzowitsch advanced variation, played at the highest level of human chess. In game 91 the engines opened the e file and castled in opposite directions. In a long PV agreement the engines exchanged most pieces and only RB vs RN remained on move 21. Leela was two pawns up a few moves later.
Stockfish got one pawn back but Leela pushed the passer on the a file to the 7th rank. The black rook prevented a queening and eventually captured the passer, however Leela captured all the remaining black pawns. It then slowly pushed a g pawn forward, Stockfish couldn't avoid queening. The game ended in a tablebase win.
In game 92 the black queen moved forward and grabbed two pawns early. Stockfish castled short, it used the black queen as a target and evals increased quickly. Leela was focused on getting its queen out of trouble, its king and rooks did not develop. Stockfish gave a rook for a bishop, and captured the other bishop with a knight fork that also forced the black king to move.
Stockfish cleared all the pawns on the queen side, the black king walked to the king side corner to hide. In a series of exchanges the engines reduced to a rook ending with Stockfish 2 pawns up. Stockfish pushed pawns forward, the win was straightforward though it took another 20 moves to mate. There were two white wins in this game pair, Stockfish leads 24-9.
Games 93-94 started in the Blumenfeld counter gambit, Dus-Khotimirsky variation, played in high level human games. In game 93 the engines opened the e file and Leela went a pawn up. Leela created a passer on the queen side, evals slowly increased as the engines exchanged a few minors. Stockfish regained the pawn and created a passer as well, both passers raced forward and both were captured.
With equal material the main issue was king safety. Leela doubled rooks on the 6th rank, then moved its queen to the g file. The pressure was too great and Leela captured the g6 pawn. Stockfish reduced to a double rook ending and Leela captured a second pawn.
Leela pushed its connected passers forward and Stockfish could not stop them. The game ended in a tablebase win.
In game 94 Stockfish pushed its center pawns forward and the center stayed closed. There were only a few exchanges after the start, evals were mostly stable. From move 25 the engines followed Stockfish's PV, which later became a very long PV agreement. The engines opened the king side, then exchanged queens. Stockfish created a central passer which Leela captured on the 7th rank, on move 47 the game reached a RB vs RB position with Stockfish a pawn up.
With such a long PV agreement and evals stable it seemed Leela could hold this position. For a while the PV showed the engines plan to trade the white f pawn and the black a pawn. However, on move 51 Leela diverged slightly from what Stockfish expected, and effectively Stockfish got one extra tempo. This was enough for Stockfish's eval to jump, it took Leela another 12 moves to see something was wrong. Stockfish pushed the black king to the back rank and the white king came forward. On move 82 Stockfish captured the black h pawn, it slowly pushed the f pawn forward. On move 103 the game reached a rook ending, Stockfish captured the last black pawn and won easily with its 3 pawns. There were two white wins in this game pair, Stockfish leads 25-10.
Games 95-96 started with an 18-ply book in the Two Knights defence, played in high level human games. White was a pawn up at the start, in both games queens were off early. In game 95 there were a few minor piece exchanges after the start, evals slowly came down. The first pawn exchange was on move 30, Stockfish created a central passer. The game reached a RRN vs RRB position, Leela blocked the black passer and opened the queen side to create a passer there. Stockfish prevented a promotion, evals were low and the game was adjudicated. In game 96 Leela pushed pawns on the king side and there was one pair of pawns exchanged. Evals came down and the engines reduced to a RB vs RN position, the game was adjudicated a few moves later.
Games 97-98 started with a 15-ply book in the Czech Benoni defence, the center pawns were locked. In game 97 there were a few pawn exchanges after the start and the b file opened. Leela went up a pawn and all knights were exchanged, exchanges continued and the game reached a BB vs BB position. Evals slowly came down, Leela managed to create a passer on the king side and reduce to a same color bishop ending. Stockfish had only one pawn accessible the the white bishop, Leela could not improve and when evals were low enough the game was adjudicated.
In game 98 there was one pair of pawns exchanged on the queen side, the position remained closed with all pieces on the board for a long time. The engines mostly shuffled and evals were stable. On move 32 the white queen moved forward on the king side, evals started to slowly increase though Leela blocked the queen's way back. There was one more pawn exchange on the king side and the first minor pieces were exchanged on move 54. The white queen got out of its trap, Stockfish moved it to the queen side within the black camp and the engines exchanged queens.
Stockfish opened the queen side and exchanged a pair of rooks. Leela tried to hold, it had to protect the weak d6 pawn and keep its pieces away from the white rook. Stockish moved its king forward on the queen side, then switched the rook to the king side after the h file opened. On move 88 Stockfish went a pawn up, Leela's defence was crumbling.
Leela preferred to trade the white knight for a rook, Stockfish gave the material back and reduced to an opposite color bishops ending. Stockfish was two pawns up, with connected passers moving forward that guaranteed the win. Stockfish wins this game pair, it leads 26-10.
Games 99-100 started with a 16-ply book, a rare KID sideline. In game 99 Stockfish gave two pawns and Leela had two doubled pawns. The engines opened the a file and Stockfish regained one pawn, evals stayed high. The engines played out a long PV agreement (with a slightly different move order for each engine), Leela captured a rook for a knight and the game reached a QRR vs QRB position. Stockfish's eval dropped and Leela's eval came down more slowly. Leela doubled rooks on the open f file, miraculously Stockfish found a safe square for its king on g4, in front of a white pawn. All the white pawns were blocked, despite being two pawns up Leela could not do anything. The engines exchanged queens and then shuffled until Leela lowered its eval for the draw rule.
In game 100 the center was locked and there were almost no exchanges after the start. Stockfish castled long and then the engines opened the g file. For a long time the engines shuffled while evals slowly increased. On move 58 Stockfish pushed the f pawn forward, Leela reacted with the b pawn to open the queen side, the engines exchanged a pair of rooks.
Stockfish had to protect the b2 pawn, while Leela needed all its minor pieces to keep the king side closed. The black king walked out of the corner to the center, and Stockfish captured the black h pawn and traded a pair of knights. The white h pawn became a passer, Stockfish pushed it forward and Leela gave a bishop to stop it.
Stockfish saw mate in its PV and Leela just gave up all its pieces. Stockfish wins this game pair, the final score is 27-10.
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