But just as Leela seemed down, she turned on god mode. Leela won 10 of the next 22 openings before Komodo finally won the 35th opening. One “busted” opening and a traded win later, Leela won another five openings to round out the superfinal. The subfinal did turn into a rout, but in Leela’s favor. The dramatic comeback from -3 to +11 speaks to the dangers of small sample size as well. Even the full 100 games is not many compared to the tens of thousands of games that engine developers regularly play when testing their patches!

There was still the “bookmaker’s subfinal”, between GM Matthew Sadler and Jeroen Noomen. The two authored the superfinal book, with Jeroen running out the victor in that match by one decisive opening. This bookmaker’s subfinal also turned out very close, and in fact uncannily resembled the superfinal: the two bookmakers remained neck and neck through most of the subfinal, involved a dramatic game 100 (Leela failed to convert a position that Komodo evaluated at +4), and ended with the same score – Jeroen wins by one opening. This time though, GM Sadler has the consolation prize of getting more wins for one engine. Jeroen only scored two Komodo wins, but GM Sadler got five. Of course, this also means that Jeroen got 11 Lc0 wins, while GM Sadler only got seven.

Next up are several more bonus matches: there are some very long time control games (6+ hours per side per game), some DFRC games (Double Fischer Random Chess, where both sides start with a different-but-valid FRC position), and exhibition games by the top engines against the best of the chasing pack. The pause gives all competitors a time to catch their breath before Season 24. Find all bonus games at https://tcec-chess.com/. 

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The fight for fourth place was less dramatic. Ethereal continued to play well, losing no openings to lower-ranked engines. It finished with 28/56, four points ahead of Stoofvlees. Stoofvlees went through a harrowing moment where it looked like SlowChess might catch it in fifth – SlowChess scored a head-to-head win in the third round while also drawing against Stockfish. Nonetheless, the 2.5-point lead at the halfway mark proved a bridge too far. SlowChess’s final score of 23/56 left it a point behind Stoofvlees, but three points ahead of rofChade in seventh. rofChade was the only engine to not win an opening in the division, but it did manage to score more draws than Berserk to finish half a point ahead.

The infrafinal is next, with Ethereal taking on Komodo Dragon in a 100-game match. Komodo Dragon is the heavy favorite, and the main question is whether Ethereal will win any openings. It is rare for the Big Three to lose to other engines, and losing an opening is even rarer. Still, with Ethereal having shown great progress in the Premier Division & 50 openings to play, it might well manage a couple. Testing is currently in progress and the infrafinal is slated to start in a day’s time. All games will be played live at the official website: https://tcec-chess.com/ and TCEC Twitch TV

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TCEC S22 – FRC5 League A live:

DivP seeded from S22 DivP, 4x DRR

 1 Stockfish
 2 KomodoDragon
 3 LCZero
 4 rofChade
 5 Stoofvlees
 6 SlowChess
+ 2 engines promoted from L1

L1 seeded from Swiss 3, 2x DRR:

 7 Berserk
 8 Koivisto
 9 RubiChess
10 Revenge
11 Ethereal
12 ScorpioNN
13 Seer
14 Igel
+4 engines promoted from L2

L2 seeded from Swiss 3, 2x DRR:

15 Tucano
16 Nemorino
17 Arasan
18 Fritz
19 Minic
20 Marvin
21 Halogen
22 Wasp
+4 engines promoted from QL

QL seeded from Swiss 3:

23 Drofa
24 Winter
25 Mr_Bob
26 Expositor
27 BlackMarlin
28 Velvet
29 Weiss
30 Zahak
31 Stash
32 ClassicAra
33 tomitankChess
34 Mantissa
35 Counter
36 ChessFighter
37 Amoeba
38 Bagatur
39 Asymptote
40 Cheese

Away from Stockfish’s rampage, the spotlight was on several fast-improving engines, especially Koivisto and Berserk (who had just missed out on promotion to Premier Division and League 2 respectively). Unfortunately for both engines, neither made it past the first two rounds. Koivisto had the misfortune of running into Stockfish in the second round, while 5th seed Stoofvlees in the first round proved a mountain too high for Berserk. Koivisto lost the first two openings against Stockfish and was promptly eliminated, but Berserk can at least point to the competitiveness of its match against Stoofvlees: although much of the first round saw the higher-ranked engines slaughtering their lower-division opponents, Stoofvlees needed tiebreaks to overcome Berserk.

Elsewhere, the big surprise package was Revenge. Seeded 12th, it served up the only “cupset” in the second round by defeating 4th seed rofChade, and then followed up with another cupset against 8th seed Igel. Revenge’s run was finally ended in the semifinals by Komodo Dragon, but it produced yet another surprise in the 3rd-place playoff by defeating Leela in game 3. Although Leela won the reverse to draw the opening, it is rare for one of the top engines to lose to lower-division opposition. If, as many predict, Berserk makes it to League 1 next season, the battle for the two Premier Division promotion spots promises to be very closely contested.

The TCEC Swiss is next. Stockfish will again be the favorite, but the nature of the Swiss format means that one of its rivals could pip Stockfish to the title if they can score well against the lower half of the field. Komodo Dragon is the defending champion, having won the previous edition of the Swiss by one point. All matches will be played live on https://tcec-chess.com

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TCEC Cup 10 pairings

FT: Chess’s icons are now Carlsen and Stockfish

TCEC Cup 10 participants

1. Stockfish (defending cupwinner)
2. KomodoDragon (sufi runner up)
3. LcZero (infi winner)
4. rofChade (infi runner up)
5. Stoofvlees
6. SlowChess
7. Scorpio
8. Igel
9. Koivisto
10.RubiChess
11.Ethereal
12.Revenge
13.Nemorino
14.Minic
15.Seer
16.Fritz
17.ClassicAra
18.Halogen
19.Winter
20.Vajolet2
21.Berserk
22.Tucano
23.Arasan
24.Wasp
25.Weiss
26.Bit-Genie
27.Drofa
28.Marvin
29.Topple
30.Pirarucu
31.Chiron
32.Zahak

Lc0’s victory reignited an old debate about whether the Premier Division was fair, as it had “failed” to select the two strongest engines for the Superfinal. Still, even Leela superfan mrbdzz agreed that the Komodo and Leela were quite close in strength, resulting in an exciting match. Furthermore, Stockfish was kibitzing the Subfinal and it pointed out several winning moves that both Leela and Komodo missed. Grandmaster Matthew Sadler agreed, pointing out that there was more of a difference between Komodo Dragon’s and Leela’s styles than Stockfish/Komodo. The Subfinal was also something of a success for GM Sadler, since he evened the “bookmaker’s score” with Jeroen – in this informal competition between the two bookmakers, Jeroen had “won” the Superfinal (there were more decisive openings selected by Jeroen in the Superfinal), but the reverse happened in the Subfinal. Read more: Matthew Sadler explains How to Maintain Your Chess Strength

With the conclusion of the Subfinal, next on the agenda is the 32-player TCEC Cup. In the last edition of the Cup, Stockfish had finished first, Leela second, and Komodo third. Although Stockfish is undoubtedly still the hot favorite to win the Cup, we’ll see several up-and-coming engines play against their higher-ranked peers. Koivisto and Berserk, who had just missed out on promotion from League 3 and League 1 respectively, will be especially keen to make an early statement on their Premier Division credentials next season. All games are available live at https://tcec-chess.com/.

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For Stockfish fans, this dominating performance is just the beginning: Stockfish 15 has just been released, and immediately afterwards, a new NNUE gaining another 2-3 elo in self-play was trained. Runner-up Komodo Dragon can also look back on Season 22 as a successful campaign. Although it was soundly defeated in the Superfinal, it did reach the Superfinal for the first time since Season 13. More: Chess’s icons are now Carlsen and Stockfish

Next up is the subfinal, a 100-game match between Komodo Dragon and 3rd-place finisher Leela Chess Zero, where the latter will try to prove that it should have been the one to challenge Stockfish in the Superfinal. Although Leela did finish well behind Komodo Dragon in the Premier Division, it was also undefeated against both Komodo Dragon and Stockfish. Leela has historically been stronger in match play than in tournaments, so we will likely witness a tough battle. After the subfinal, the chess fans can expect the Cup, the Swiss, and Fischer Random Chess event. All games will be played live at https://tcec-chess.com/

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Game review

Here is game 22 of Season 22, with analysis by GM Matthew Sadler Replay: https://tcec-chess.com/#div=sf&game=22&season=22 Video: Youtube

Stockfish is on track to set two TCEC records: the most decisive Superfinal ever (the current record is +20 over 100 games, also set by Stockfish against Komodo in Season 12), and an “undefeated” Superfinal where the only games it loses are to “to the opening book”. Barring a miracle, the second half of the Superfinal will be one of damage control for Komodo Dragon, as it fights to avoid being on the wrong end of history. Afterwards, however, it will get the chance to redeem itself against Leela in the Subfinal.

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TCEC Premire division final standings / Report after DRR2 / Report after DRR3

Stockfish did not have it easy, and for much of the division it trailed Komodo Dragon after the latter benefited from a Scorpio blunder in the first double round robin (DRR) to record a 2-0 double kill. Still, Stockfish turned in a near-flawless performance – it won all but two white games it played against the bottom five engines while successfully drawing every game with black, and further scored a head-to-head win against Komodo Dragon. It finished the division as the only engine not to lose a game. Komodo Dragon was almost as dominant against the lower half of the field, but the loss to Stockfish, coupled with a difficult loss to Stoofvlees in the third DRR, left it half a point behind in second. Season 21 runner-up and fan favorite Leela Chess Zero finished third. It was the only engine not to lose to Stockfish, but it fell behind in the first DRR when it lost to rofChade in spite of winning the reverse, and its chances of reaching the Superfinal dimmed further when it failed to convert superior positions against Stoofvlees and Slowchess in the second DRR. It finally finished third, 3 points behind Komodo Dragon, but 8 points clear of rofChade in 4th place.
Speaking of rofChade, this engine returned with NNUE this season after playing without it in the previous two seasons. The effect was immediate, as after getting relegated to League 2 in Season 21, rofChade not only navigated its way to Premier Division but also pipped perennial dark horse Stoofvlees into fourth place. Stoofvlees had a bad start in the division, losing openings to Slowchess and Igel, before eventually clawing its way back to finish fifth. Playing in the Premier Division for the first time, newcomer Slowchess flirted with relegation, but capitalized on ScorpioNN’s misadventures to survive the drop. ScorpioNN had been involved in relegation battles for the past several seasons, and its streak finally ended this season when it lost twice with White – in addition to the blunder against Komodo, ScorpioNN crashed once against Igel. Igel, the only engine playing without an update, still managed to win an opening against Stoofvlees, but was unable to capitalize on the unexpected gift from ScorpioNN’s crash to finish last.
Next up is the infrafinal, between the 3rd and 4th place finishers – so Lc0 and rofChade. Leela is starting as the heavy favorite, with most viewers predicting a Leela victory by roughly 10 points – a very substantial margin of victory given the shorter length of the infrafinal.

After the infrafinal, Stockfish and Komodo Dragon will take the stage. It will be the first Superfinal since Season 13 in which no GPU-based neural-network engine has competed in, and the first Superfinal between two NNUE engines. It will also be the first time Komodo – still the second-most successful engine in TCEC – has reached the Superfinal since Season 13. Stockfish developer Michael Chaly has already predicted a crushing victory for Stockfish.

Special thanks to Cato the Younger

This Premier Division was the last one to have a book by Nelson Hernandez aka Cato the Younger. His contributions to TCEC openings during many seasons and events have been invaluable. Thank you, Cato!