TCEC C960 FRC5

Earlier this month on my main blog, I posted Stockfish Wins TCEC Swiss 3 and CCC17 Blitz (July 2022). After 'TCEC Swiss 3':-

The site then launched FRC5, which is currently in the four engine 'Final League' stage (KomodoDragon is missing).

The 'Final League' served as a qualification event for the two engine 'Final Match'. The following chart shows the crosstables for both of the 'Final' events, which have completed.

Top: Final Match
Bottom: Final League

In the 'Final League', Stockfish and LCZero finished in a tie for 1st and 2nd to qualify for the 'Final Match'. That result came about after they tied their individual mini-match +4-4=0 and crushed the two last-placed engines in their other mini-matches. In the 'Final Match' Stockfish beat LCZero +17-13=20.

As for the remark, 'KomodoDragon is missing', the other member of the current engine triumvirate was eliminated at the semifinal stage. Through a specific combination of first and second place finishes in the groups of the preliminary stage, all three engines played in the same four-engine semifinal group. LCZero finished a half point ahead of Stockfish, which was a full point ahead of KomodoDragon, thereby eliminating KomodoDragon. For more about the specifics of the competition, see:-

• TCEC FRC 5 (wiki.chessdom.org), and
• TCEC FRC rules (ditto).

An important section of the rules is worth highlighting:-

4. Openings books
a. All matchups until the Semileagues stage will be played from a randomly generated FRC aka Chess960 start position.
b. For the Semileagues, the Final League and the Final a shallow book will be used.

What does 'shallow book' mean? I couldn't find an explanation on the TCEC Wiki, but the site's !commands inform,

!mob • MOB - Minimalistic Openings Book made by Kan. The idea is to leave lots of choice to the engines and be as shallow as possible while providing an optimum of variety.

I imagine that definition was developed for the traditional start position SP518 and has been reused for chess960. My post on the previous event, TCEC C960 FRC4 (January 2022), looked at TCEC practices for chess960 opening books. To adapt a phrase from that post,

The researcher behind the 'shallow' analysis should make available his full analysis showing which positions were eliminated for which reasons.

That FRC4 post also referenced a couple of my own 'Iceberg' posts (November 2021) analyzing engine runtime data from TCEC FRC3. Add FRC5 to the backlog of events for this sort of analysis.