TCEC Swiss 7 will be the first event of the season and will be the strongest chess event (ever!). A total of 44 participants, including the Swiss 6 champion LcZero, the top rated Stockfish and exciting newcomers Ceres, PlentyChess, and Patricia, will battle it out for the title in this record breaking Swiss.

Swiss 7 will be daily live on the official website of TCEC, in video format on TCEC Twitch TV, a broadcast on our favorite game server Lichess, and news reports on Chessdom.

Breaking the ELO record

ELO records depend on multiple factors. They include, but are not limited to, the formula used, the field, the sample size (number of games), and even the configuration (when talking about computer chess). Luckily, TCEC has the precise measurements to detect rating jumps in chess software. And the jump in Swiss 7 is huge! With high confidence we can claim that this is by far the strongest chess event in history.

Putting the record into perspective and “human terms”: imagine a classical tournament at a time where Carlsen and Kasparov close to 3000 ELO and Caruana, Aronian, Firouzja, Topalov, Anand, So, Nakamura, Kramnik, and Giri are all above and around 2900 ELO. Now this is what we are viewing in computer chess at TCEC Swiss 7!

Here is a comparison of the top 10 participants in Swiss 1 and Swiss 7 events. The difference of rating jumps is even bigger among the rest of the participants.

Breaking the participation record

The state of computer chess – thriving! The sector has experienced a recent !boom with the development of new technology and ideas. For the first time ever TCEC had more applications than the event can accommodate. As a result, various engines had to undergo qualifications tournaments, raising the average ELO of the field even more.

TCEC Swiss 7 seeding and participants

This is the full participants list of TCEC Swiss 7 according to seeding. The seed number is determined according to the season rules, starting with the previous champion of TCEC – LcZero

1. LCZero (defending champion of TCEC Swiss 6)
2. Stockfish (Season 26 league champion)
3. Berserk
4. KomodoDragon
5. Ethereal
6. Seer
7. Ceres
8. RubiChess
9. Stoofvlees
10. Caissa
11. Obsidian
12. rofChade
13. Viridithas
14. Igel
15. Revenge
16. Arasan
17. Clover
18. Lizard
19. Velvet
20. PlentyChess
21. Minic
22. Uralochka
23. Stormphrax
24. Ginkgo
25. DeepSjeng
26. BlackMarlin
27. Marvin
28. Altair
29. Equisetum
30. Booot
31. Weiss
32. Tucano
33. Halogen
34. Renegade
35. akimbo
36. Texel
37. Winter
38. Devre
39. ChessFighter
40. Patricia
41. Princhess
42. ice4
43. 4ku
44. Heimdall

Which record is not broken?

TCEC Swiss 7 is part of the 27th edition of TCEC. It is one of the four titles that the engines can compete for, namely the Swiss, FRC, Leagues, and Cup titles. Inherently, every season is stronger than the previous one. Engine chess is booming, authors are more active than ever, technology is developing, ideas are growing. This season and the TCEC Swiss 7 event seems to break all records, but one. It is the TCEC Leagues S11 record, where the Premier Division average rating grew by 150+ ELO points. The average ELO of top 10 engines then was 3351 points, a full 150 points jump.

Another record in sight is the audience. The most viewed season of TCEC was 2 million people audience. Back then it was fueled by Carlsen’s World Chess Championships success. Since then TCEC seasons have crossed 1 million viewers several times, but has never been close to this record.

The match started with Leela taking the lead 2,5-0,5 after winning a game with white in round 1 in Paulsen attack and a second game in round 3 in Sicilian Najdorf. Stockfish reacted, bringing the score level by game 10 and taking a two point lead afterwards. And just when everyone thought Stockfish might be on the way to an easy title, Leela Chess Zero showed that the games from the first rounds were not a coincidence and returned a point.

Replay the decisive games

Lc0 – Stockfish (Center game, Paulsen attack) 1-0
Lc0 – Stockfish (Sicilian Najdorf) 1-0
Stockfish – Lc0 (Sicilian Najdorf) 1-0
Stockfish – Lc0 (King’s Indian, Averbakh system) 1-0
Stockfish – Lc0 (Pirc, Austrian attack) 1-0
Stockfish – Lc0 (French, Tarrash) 1-0
Lc0 – Stockfish (King’s Indian, 5.Be2)

Currently the score is Stockfish 10,5 – Leela Chess Zero 9,5, with a game 22 (a Budapest) going on. Games are going on 24/7 and you can follow then with detailed analysis at the official website here

Unfortunately for the romantics, the first round served up no “Cupsets”. Stoofvlees struggled a little against Marvin, which is always tense because Stoof has a history of “oofing” and losing, but it didn’t happen this time. Round 2 saw a mini-cupset as 14th seed Koivisto put 6th seed Slowchess to the sword, but this wasn’t too surprising either because Koivisto had suffered from a major bug in the previous season and was seeded unusually low as a result. The rest of the matches all proceeded like clockwork as the higher-seeded engines bested their opponents.
But if people were beginning to lose hope, the semifinals brought a real surprise when Stockfish lost an opening to Komodo Dragon. Komodo Dragon is a strong engine, but it has not won an opening against Stockfish for a long time, with the -19 +0 =31 minimatch loss to Stockfish in the Season 22 superfinal an especially bad memory. There was no fairytale comeback this time as Stockfish recovered to win 6-4, but the dropped minimatch did make it seem like the otherwise-untouchable Stockfish can be beaten. Was it a blip, or was it a sign that possibly, just possibly, that Stockfish would fail to win the Cup? In the other semifinal, Lc0 dusted Ethereal away 5-3 to take up the reins as Stockfish’s final opponent. Things started out badly for Leela as Stockfish drew first blood in games 3/4, winning a French Defense, no less. Historically it had generally been Leela who was better at that opening. But in game 7, Leela demonstrated superior positional understanding after Stockfish failed to sense the danger of allowing its Bishop to be forced into a corner.

(Caption) A critical moment in game 7. White’s position is clearly pleasant, and Leela’s +0.97 evaluation is very high by Leela’s standards, but the game isn’t over by any means. Stockfish chose 19…O-O, allowing 20. h6 Bh8. Black’s Bishop is in trouble and the continuation 21. f3 f5 22. g5 made it even more miserable. Although superficially it looks like Black can open a diagonal for the Bishop with …c5, White only has to respond with c3 to keep the Bishop trapped.
This sparkling win tied the match. A tense series of draws later, Leela won game pair 15/16 to win the match. The mighty Stockfish was beaten for the first time in what feels like forever, and Leela won its first title since Season 17.
Next up was the Swiss. This format rewards engines that can reliably beat lower-rated engines, and Leela’s developers submitted a version with dynamic contempt for the first time. This feature is intended to make Leela play for wins against lower-rated opponents, and had already been used to great success by Stockfish (back when Stockfish used handcrafted eval) and Komodo Dragon. For the lower-rated engines, the Swiss took special significance because it affected placing in the Leagues – 22 spots in the Leagues were decided by placing from the previous season, with four more spots going to the top-placing non-qualified engines from the Swiss. 
I could highlight a lot of things, but one thing overshadows them all. In the very first round, Cup winner Leela produced the following brilliancy against QL engine Cheese:

Something had clearly gone wrong with Leela’s dynamic contempt. Needless to say Cheese won easily from this position, and although Leela also won with White to tie the match, it was already behind its rivals – both Stockfish and Komodo Dragon won their opening matches against strong opposition. When the same thing happened to Leela again in round 2 (this time against Drofa), it looked briefly like Leela might not finish in the top 3. Fortunately for Leela fans, the “Leelabug” doesn’t affect Leela’s play against strong engines, and the Swiss format even meant that Leela faced weaker opponents for the next few rounds. Leela steadily fought its way up the table to eventually finish 3rd. For the other members of the Big Three, Stockfish continued to show some weakness when it lost games – but not matches – to Revenge and Scorpio, although it did win the head-to-head against Komodo Dragon. That one point swing, combined with Leela’s dropped half-points against Drofa and Cheese, turned out to be just enough to give Stockfish the tournament victory – its final score of 15.5/22 was exactly one point ahead of Komodo Dragon and Leela on 14.5/22.

For other competitors, the qualifiers to League 2 turned out to be Velvet, Expositor, Wasp, and Uralochka. Velvet played some strong chess, including a 2-0 double kill over Expositor, to finish the highest of the four. Meanwhile, Expositor benefited heavily from the Swiss format when it was paired against the bottom three finishers, scoring 5/6. Its 11.5/22 score actually placed it above League 1 engine Berserk, who had the misfortune of being matched against all of the Big Three. The two 4k engines (so-called because their size is limited to 4 kilobytes) ice4k and 4ku finished solidly last, well off the pace. The 4k handicap is a tough one. 4ku’s developer even deleted the “print eval” line to save space, making 4ku games rather mysterious to watch.

Next up is League 2, where the four qualifiers will face several seasoned competitors, the biggest names being former Premier Division engines Igel and Fritz. Unsurprisingly, both engines are favorites for promotion. Testing is currently under way, and the league is slated to start right after. All games will be played live at https://tcec-chess.com/

Article by Low

TCEC Season 23 so far: Full standings Premier Division / It’s Stockfish vs Leela for the TCEC Superfinal / Ethereal trailblazes TCEC League 1 / Minic convincingly wins TCEC League 2

As has been the case for several years, engines had improved to the point where one needed openings with heavy bias to separate them – that is, the opening book provides a comfortable advantage to one side, and the competitors take turns to play that side. Sometimes the bias is too high, and the result is a “busted” opening where both engines win when given the advantage. The Superfinal started with such a busted opening, but Stockfish drew first blood in the very next opening by winning with White while drawing with Black. When Stockfish notched another win in the fourth opening, it looked like the Superfinal might turn into a rout. But the seventh opening served up a surprise: after Leela had finished off a dodgy variation of the Sicilian Rossolimo with White, it was Stockfish’s turn to try to make something happen with the White pieces. Stockfish mounted a kingside advance that forced Leela’s king into the open, and it was looking like it would be a routine victory for Stockfish. And then this happened:

As strong as engines are, sometimes the human brain is still superior! Leela held out to win the opening and cut Stockfish’s lead to 1 point. There were murmurs among Leela’s fans. Could she do it?
Unfortunately for Leela’s fans, that bubble burst quickly. Stockfish won the eighth opening … then the ninth … then the twelfth … and then won some more. By the midway point, with Stockfish up +7, the only question was whether Stockfish would crush Leela as badly as it had crushed Komodo Dragon in the Season 22 superfinal. Stockfish had won by +19 then, so it was behind time, but the fact that some of more high-bias openings had still to be played gave Stockfish fans some hope. Stockfish quickly won another four openings, but then it misevaluated another blocked position to hand Leela her second won game pair. The chance was gone, and Leela emerged from the Superfinal battered, but still less battered than Komodo Dragon.

There was still the “bookmaker’s Superfinal”, between the two bookmakers of the Superfinal – GM Matthew Sadler & Jeroen Noomen. Jeroen took the early lead, but the 7th opening was GM Sadler’s, so he had the only Leela victory in the books. The two remained neck and neck as the superfinal progressed. The second Leela victory went to Jeroen, but several Stockfish wins went to GM Sadler to keep the score level. The score remained unclear all the way to the final game 100: if it ended decisive, Jeroen would win, while if it ended drawn, GM Sadler would win. Stockfish had the White pieces in a Czech Benoni, an opening that usually leads to blocked positions. Stockfish’s eval was soon above +2, but since Stockfish had misevaluated several such positions earlier in the Sufi, it was unclear if Stockfish could actually convert. For the longest time it looked like the game was just shuffling. Both Stockfish’s and Leela’s evaluations kept rising, but even the kibitzing GM Sadler could not tell what was happening. Finally, after 60 moves, Leela played 60…b5, opening lines and going down in defeat. If Leela were human, we would say she cracked under pressure, except Stockfish also predicted Black would play 60…b5. Go figure – this mysterious game defies human understanding, and I for one am curious what Leela’s decisive mistake was. 

In any case, Stockfish’s victory gave Jeroen the Superfinal win, 11 decisive openings to 10. It is Jeroen’s second consecutive victory – he also won the Season 22 bookmaker’s Superfinal 11-8. Jeroen has been making books for engine competitions for a long time, so he surely has an advantage in experience, but GM Sadler is catching up.
The next major event is the Subfinal – played between the loser of the Superfinal (Lc0) and the winner of the Infrafinal (Komodo Dragon). While Stockfish is clearly in a league of its own, this match is likely to be much more contested. The two engines last played each other in Season 22, with Lc0 emerging victorious (+24 -15 =61). Will Leela win again this season? Most viewers certainly think so, albeit by a smaller margin of +1 to +5. The Subfinal is slated to begin on 19 November. Catch the games live at https://tcec-chess.com/

Article by Low

Komodo wins infrafinal by 19 games, Ethereal wins a game pair

There was no shock upset in the TCEC Season 23 infrafinal as Komodo Dragon cruised to a routine win. Played with the Season 18 opening book, the infrafinal started with a draw before Komodo Dragon won four of the next five openings to take a big lead that it never gave up. With the infrafinal unfolding as expected, the question quickly turned into whether Ethereal would do better than rofChade did last season. In season 22, Lc0 had won with +21 -1 =78 vs. rofChade. Would Komodo Dragon beat that margin of victory, and would Ethereal win a game pair? Ethereal played White first in every game pair, and since most openings heavily favored White, it would be the one to strike the first blow, making for tense games should Ethereal win.

Ethereal notched its first win in game 15, although it failed to hold the reverse. When Ethereal scored another win in game 17, it had already scored more wins than rofChade did. However 1-0, 1-0 game pairs are still not won game pairs, and Komodo Dragon has historically been better than Leela at winning against lower-ranked engines. By the halfway mark, Komodo Dragon had won 11 game pairs, lost none, and was on its way to a larger margin of victory than Leela had managed. All that changed in two critical games 54-55. Out of a Philidor in which Black fianchettos on the kingside, Komodo castled kingside, against which Ethereal mounted a kingside advance. The resulting attack led to heavy complications which Ethereal navigated better to score a win. In the reverse, Ethereal chose a different plan, castling queenside and avoiding the kingside attack of the previous game. This time Komodo Dragon navigated to a comfortable pawn-up endgame, but it was unclear how White could make progress. As the moves shuffled away, Ethereal drew the game to score a memorable game pair win. 

This won game pair started a mini-revival for Ethereal as it drew seven consecutive game pairs, but eventually Komodo Dragon turned on the heat to win 8 of the last 15 openings. It was too late for Komodo Dragon however, and Ethereal escaped with a -19 score, one better than rofChade’s -20. 

The Superfinal is next, with Stockfish taking on Leela. Stockfish is the heavy favorite – so much so that the main question for most viewers is not who will win, but by how much. Most viewers are predicting Stockfish will win by the Season 21 score of +11 to +15, but also that Leela will win between 1-5 openings. Although this might sound one-sided, when we consider that Stockfish rolled over Komodo Dragon by +19 while losing no game pairs last season, if this result pans out, it will still be a more competitive match. For the two bookmakers Jeroen Noomen and GM Matthew Sadler, there will always be a competition. Whose openings will yield more decisive game pairs? Jeroen won the S22 “bookmaker’s sufi” by 11-8, and Matthew will undoubtedly be looking to even the score. Testing for the superfinal is currently under way, and the superfinal is projected to start in a day’s time. Catch all games live at https://tcec-chess.com

Article by Low

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

Article by Low

Away from the top boards, Ethereal has strongly established itself in 4th. Although (like everyone else) it was crushed by the Big Three, it won two openings against both Berserk and rofChade, while also beating Stoofvlees once. With 15/28, it is the only engine outside the Big Three with a >50% score. 5th-placed Stoofvlees also won some openings against SlowChess and rofChade to stand a point behind Ethereal and 2.5 points clear of sixth-placed SlowChess. Barring a minor miracle, we’ll be seeing either Ethereal or Stoofvlees in the infrafinal.

That leaves three engines fighting to survive relegation. At the half-way mark, SlowChess is in the lead, but is only half a point ahead of Berserk. Berserk is in the relegation zone, but it is the only one of the bottom three engines to have won an opening against another bottom three engine, defeating rofChade in the first round. rofChade is last, a point away from safety. Still, it scored a rare win against Komodo Dragon in the first round. Although it also lost the reverse, it is rare for the Big Three to lose to anyone other than themselves. rofChade might make it yet.
The second half is estimated to begin in a couple of hours as of time of writing, around 6am UTC 9 October, with rofChade wielding the white pieces against SlowChess. Catch all live games on the website: https://tcec-chess.com/ and TCEC Twitch TV

Article by Low

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