Stockfish Wins TCEC S24; Engine Mysteries

For this post on the world's top two engine vs. engine competitions, four weeks have passed since the previous post: TCEC S24 Sufi, CCC20 Rapid - Both Underway (April 2023). Here's a summary of the engine action reported at that time:-

TCEC: Stockfish won the 'DivP Playoff' with an undefeated score; LCZero finished second to qualify into the S24 Superfinal (aka Sufi). After 40 games in the 100-game Sufi, LCZero has a slim one point lead. • CCC: The 15-engine OpenBench event, titled 'OpenBench Interlude #8 - All Hands', was won by Berserk. This was followed by the first stage of the 'CCC20 Rapid' event, renamed from 'Newcomers' to 'Entry League', which was followed by 'Qualifier #1' and 'Qualifier #2'.

A lot can happen in a month, but the TCEC and the CCC both leave plenty of trail markers to follow their evolutions. Following is a summary of the past four weeks, including a couple of mysteries.

TCEC: Stockfish beat LCZero +20-16=64 to win the S24 Sufi. How many wins in a row does this make? If we go back to the previous Sufi, TCEC S23, CCC19 Rapid : Stockfish Wins Both (November 2022; 'Stockfish beat LCZero +27-10=63 to win its sixth straight Superfinal'), and add one, we get seventh straight Superfinal.

After the S24 Superfinal, the site conducted the following events (the links are to posts on this blog for the the previous iteration of the same event):-

• S24 VVLTC Bonus, 'Very Very Long Time Control'; see TCEC More Interludes; CCC19 Bullet Underway (December 2022; 'Stockfish won the VVLTC, then drew the two-game SVVLTC with LCZero')
• S24 Kibitzer Bonus; LCZero dag-master-[...] beat Stockfish master-[...]. The purpose of this match is a mystery.
• S24 4k 2, TCEC: 'Engine maximum size is 4 kiB (4096 bytes)'; see TCEC Cup 11 Underway; CCC19 Bullet in Semifinals (January 2023; 'Engine ice4 won the S23 4k tournament ahead of 4ku and three other engines')

The site is currently running the 'S24 4k 2 Final' between 4ku and ice4, the engines that finished 1st and 2nd in the six-engine 'S24 4k 2'. With one game left to play, ice4 has a one point advantage. The next scheduled event is 'FRC 6'.

CCC: After the 12-engine 'CCC20 Rapid Qualifier #2', the site ran two more 'CCC20 Rapid' events, a 12-engine 'Main' and a 6-engine 'Semifinal'. The three engines promoting from 'Qualifier #2' all finished in the bottom half of 'Main', while the top half promoted to the 'Semifinal'. The 'Semifinal' was won by Stockfish, ahead of Lc0 and Dragon. Stockfish qualified for the 'Final', while the other two engines will play a 'Challenger Match' to determine the second finalist.

Before the last two 'CCC20 Rapid' matches, the site conducted a series of 'Mystery' matches. These were described as:-

Mystery vs ... Berserk? Ethereal? Dragon? Lc0....? Until losing.

Mystery beat Koivisto by a wide margin and is currently leading Berserk.

[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. • NB: Leela = LC0 = LCzero; Dragon = KomodoDragon]