TCEC S15 Final: SF vs. Leela; CCC8 S1 at 3/4 Mark

Another Monday post on this blog means another update on two important, ongoing engine-to-engine competitions. I'll summarize last Monday's report, TCEC S15 DivP Nears Finish; CCC8 [S1] Half-Way, with a short paragraph:-

TCEC: The season 15 premier division is in the final round of play with Stockfish holding first place, Leela second, and the other engines trailing by a considerable margin. • CCC: CCC8 uses an escalation format [...] As of this writing, a little more than half of the engines have started play, and the final result is anyone's guess. The official schedule projects 1104 games total.

I'll come back to that last sentence when I give the current status of the CCC.

TCEC: The premier division finished with the same relative positions given last week, as shown in a small version of the final crosstable below. Stockfish finished two points ahead of Leela (aka LC0, LCzero), although Leela won their individual match by the score +1-0=5.

In the last event for S15, Stockfish and Leela will play a season-ending final match (aka superfinal, sufi) for the second time to determine the best engine on the planet. See Stockfish Wins TCEC S14; CCC6 S2 Underway (February 2019) for this blog's report on the first final match, which was as close as a decisive match can be.

TCEC S15 Premier Division

Among the also-rans, the result of AI/NN engine AllieStein was the most remarkable. Starting the season in division 4, the lowest of the five divisions, it consistently finished in the top-2 for each successive division, eventually qualifying into the premier division. There it tied for 4th/5th with Houdini. It has been less than a year-and-a half since Houdini won TCEC S10, around the same time that DeepMind's AlphaZero burst into the chess world's collective consciousness. I reported on both of those events in Houdini, Komodo, Stockfish, and AlphaZero (December 2017). AlphaZero was the first AI/NN engine to compete at the level of the traditional engines; Leela was the second; and AllieStein is the third.

Before the final match, the TCEC will be holding another cup event, as announced in TCEC Cup 3 - pairings and information (chessdom.com):-

The cup holder Lc0 is going to defend its title in a race with the top 32 engines of the ongoing season. [...] The main challenger of of Lc0 will be Stockfish. It starts at the other end of the brackets and the two can meet only at the final

Before cup play starts, the TCEC is holding a couple of filler (aka bonus) events. I couldn't find much about these events and what I could find wasn't helpful, so I'll say no more.

CCC: Getting back to the summary of last week, I called it the 'Half-Way' point for the preliminary stage of CCC8. In fact, the CCC escalation format makes it difficult to pinpoint the progress of an event. The first two engines meet in a mini-match. Then a third engine enters the competition and plays the first two, then a fourth engine plays the first three, and so on. This procedure introduces all sorts of complications for the spectators. Given that 24 engines are competing, we can calculate that 276 mini-matches are played during the event. Since each match consists of four games, we get the total of 1104 games foreseen for the entire event.

As of this writing, 18 engines have started play in CCC8; the most recent was Leelenstein. Nearly 590 games have been played. That means 75% of the engines have started play, but somewhat more than half of the games have been played. Houdini and Antifish are at no.1 and no.2, unfortunately a meaningless observation. Next week's Monday post also won't provide much insight into the eventual final standing, which will qualify the top four engines into a multi-stage round robin.

[For further information from the various stakeholders in the engine-to-engine events, see the tab 'TCEC/CCC Links' at the top of this page.]