In today’s video GM Sadler looks at Leela defeating Obsidian, a game from TCEC Swiss 7, dubbed as the strongest ever event. Leela is currently leading the event, as joint leader with Ethereal and Stormpharx. Along the way, Leela defeated the possibly third strongest engine Obsidian. Here are the details, in an instructive video by GM Sadler.

It could have been an 11-way tie for first, had Halogen and Leela split the points. However, Leela managed to outplay Halogen in a QGD Slav and jumped ahead of competition.

The standings bring exciting matchups in the next round , where we will see Leela Chess Zero – Stockfish and Ceres – RofChade

Follow TCEC live: Official website / TCEC Chess TV / Lichess / Chessdom live More: Interview with Gabriele Lombardo from Obsidian

Standings

1. Leela Chess Zero 4,5/6

2-10. Ethereal, Stockfish, Ceres, Ginkgo, rofChade, Stormphrax, Viridithas, Devre, and Stoofvlees 4,0/6

11-17. Halogen, Velvet, Berserk, Minic, Obsidian, Caissa and Igel 3,5/6

Total 44 engines, full standings here

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

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/. 

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

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