Leela Chess Zero (LC0), an open source adaptation of DeepMind’s recent Alpha Zero artificial intelligence demonstration project, will compete in TCEC’s Season 12. In so doing it will become the first chess-playing neural net in history to publicly challenge traditional human chess programming since the days of Turing and Shannon. This epochal event will commence April 18th at 19:00 CET. Follow the games on the official website

Leela Chess Zero is an open source project by large community of programmers, with the goal to build a strong UCT chess AI following the same type of techniques as AlphaZero, as described in Mastering Chess and Shogi by Self-Play with a General Reinforcement Learning Algorithm i.e. follow in the steps of Alpha Zero by using the contributions of the computer chess community. Leela Chess Zero uses Stockfish’s position representation and move generation although no heuristics or prior knowledge are carried over from Stockfish.

Leela Chess Zero is going to play in TCEC Season 12, The entry is possible due to Defenchess (Div 3) withdrawing in the last moment. This means ChessBrainVB will automatically promote to Division 3 based on it’s Season 11 performance, and this in turn opens a place in Division 4 for LC0 to enter the competition.

More about TCEC S12: Official website / Twitch video channel / Full list of participants

Test match of LC0 vs a TCEC engine

Leela Chess Zero is a rather new but rapidly developing project. With every version released the strength of the engine increases. But is it ready for TCEC and the division structure of the championship, running only on CPU and observing the TCEC rules set? TCEC is built for projects in active development of Elo strength estimated at 3000 or more. To prove that LC0 is ready for the event it was pitted against two of the Division 4 engines in the field and a classical engine.

Against Scorpio, LC0 achieved +4=3-13 (5.5 points) and a performance rating of ~2700 ELO. Among the wins of LC0 was a fantastic miniature on the black side of Caro-Kann Tartakower with 6.c3, a 36 moves win with white in Spanish: Closed, Smyslov, 12.Nf1 Bb7, and a win in King’s Indian: Fianchetto, Classical, 9.h3 Qb6 10.c5 See the full list of games of the Scorpio – LC0 match.

In a mini match against Fruit, Leela Chess Zero was more than convincing with +4 = 1 -1 and a performance of over 3000 ELO. Against the classical version of Stockfish 1.0, Leela Chess Zero achieved +7=3-10

The version of Leela Chess in TCEC

The version of Leela Chess Zero that will participate in TCEC is LC0 ID 125. This is the same version that played the test matches vs Scorpio and Fruit. For more about LC0, meet the experts and contributors in the TCEC chat

Leela Chess Zero will run entirely on CPU during TCEC Season 12. There are plans to make a match between a higher level engine and Leela Chess Zero on GPU/TPU, however, that entirely depends on the support of the community

More about Leela Chess Zero in TCEC

The “Zero” in LC0 signifies no human chess knowledge is added. This is the key difference between neural net engines and standard chess engines. Technically, this will still be true for the TCEC version of LC0. However, one modification will be made to LC0′s TCEC version. Tests have shown that LC0 performs as much as 300 Elo better when paired with 6-man Syzygy tablebases, which are not human knowledge but rather a table of endgame computations. Many other engines in the TCEC field refer to tablebases and we deem it most fair (and most fun) to have LC0 compete with tablebase access as well.

The LC0 project requires a huge amount of computation and the only feasible way for LC0 to advance is as a distributed project. If you want to help Leela achieve its full potential please visit https://groups.google.com/forum/#!forum/lczero or the Leela Chess wiki