Some surprises in the TCEC Premier Division, Stockfish still leads

Article by Jeydra

For engine chess lovers, the Premier Division of the past several TCEC seasons have entered a routine – Stockfish wins, Leela finishes second, and all there is to wonder is which engines relegate. Most viewers predicted more of the same this season, with over 80% of viewers expecting another Stockfish-Leela Superfinal. And indeed the division started out that way, with Stockfish and Leela both winning their opening match. It wasn’t until game 19 when the first sign something unusual might happen: Leela went down to Obsidian in a French defense (!?) and then failed to win the reverse. For an engine that has won many game pairs against Stockfish in this very opening, this was a major surprise. Meanwhile the newly-promoted engines Integral & PlentyChess, who are often immediately relegated back to League 1, turned in more-than-credible performances – especially Integral, who won four opening pairs out of seven in the first round to place second.

But if Leela was wobbling, round two served up even more surprises when Stockfish lost to Integral in game 63. In engine chess, losing a game is not that bad as long as one wins the reverse, but Stockfish losing at all is uncommon, especially against a non-Leela opponent, and especially with the opening evaluations under 1! As we waited for the reverse game, Stockfish stayed in first place by putting the weaker engines to the sword – until it got hit by a double whammy: first Integral held the reverse, and then Leela won game 94. These two game pairs, the first Stockfish has lost in Premier Division since Season 24, briefly put Integral into first place. Integral’s fairytale run crashed down to Earth shortly afterwards when it lost to Leela, and again to dark horse Obsidian. Still, at the halfway point, it is in third place, tied with Leela on points and a point behind Stockfish. We might yet see something other than a Stockfish-Leela superfinal.

As the top engines do battle for the superfinal, the bottom three are more or less established: Berserk, Ethereal, and longtime Premier Division engine Komodo Dragon. If Komodo Dragon is relegated, it’ll be the end of an era: it has been part of the top division of the TCEC since inception. Still, it shows how quickly engine chess is advancing. All of the bottom three are either inactive or semi-inactive. At the Top Chess Engine Championship, you update or you relegate. There is no middle ground. 

As the TCEC Premier Division continues, you can follow it at: Official website / TCEC Chess TV / Live on Chessdom

Here are the momentary standings at TCEC