Leela Chess Zero Blog

ROUND 11
This round saw Leela drawing rather not that comfortably a strong engine and currently in the top 8 engines(the top 8 of 24 engines are promoted to next round) Andscacs. In a strange game in semi-Slav, Meran variation, Leela playing black actually lost the Queenside and was strong in the center opposite of what one actually expects in this opening. By move 30 position for white seemed very good with total dominance on the Queenside and a Pawn of black ready to fall. Yet Leela defended very well and gave the exchange sacrifice giving her Rook for a Knight and because of the exposed white King managed to make a difficult draw.

Some statistics about Chess.com Computer Chess Championship till now.

Game length Frequency
1-0 =-= 0-1 1-0 =-= 0-1
All games 78 94 76 33.8% 46.2% 19.8%

**

Shortest wins (White)**
1: 1-0(35) Pedone 1.8 3090 - Crafty 25.2 3283
2: 1-0(42) Lc0 17.11089 3300 - Nirvana 2.4 3090
3: 1-0(51) Ethereal 10.88 3283 - Crafty 25.2 3099
4: 1-0(53) Shredder 13 3287 - Nemorino 5.00 3287
5: 1-0(53) Xiphos 0.3.17 3179 - Nirvana 2.4 3099

](https://www.chess.com/computer-chess-championship)

ROUND 9

It was the round of draws, with only 4 games to be decided and 8 draws. All top 6 engines drew their games.
Ethereal had a pleasant game as it crashed the aging Crafty while Shredder couldn’t take anything out of the opening it had and Laser had no problems so game ended a draw.
A clash of titans happened in this round between Stockfish and Komodo, in a game where Stockfish created a very good attacking position though a little closed and Komodo deployed a very good defense. Stockfish tried for the breakthrough but Komodo defended excellently and the game ended in a draw.
Leela played against Senpai with black and while it managed to create a complicated game with attacking prospects against Senpai’s King, never really managed to go beyond that due to some inaccuracies by playing many moves with her King and delaying the attack. Yet after some shuffling she had a chance to try to push for the win with 59…Kf8! but Leela missed it and played 59…Rc1? that is a drawish.

The Chess.com computer Chess championship continued with most top engines winning their games so little things changed in the top positions.
Leela had a good performance winning 2 games and drawing the 3rd against the mighty Stockfish! It was a boring draw though, with no big fights whatsoever.

Traditional Chess engines with classic Alpha-Beta search, sometimes have huge problems with some positions that require deep planning and understanding of the position. This is because they try to search all possible moves in a position and then their replies and then all the replies of the replies, etc. They discard most moves of course with clever algorithms that prune almost all moves but a few that they focus on. With a cost of course to discard a move, not good looking at first sight, but that after many moves ahead it proves to be a very good one. Traditional engines also have a handcrafted evaluation function. That means in order to judge a position they have to rely on human rules for it, e.g bonus for Rook on open file, bonus if a Pawn is on 6th rank etc, etc.

CCCC rounds 3 and 4 and 5 were finished. Houdini is on the lead with 5.0/5 while Leela is doing well with 4.0/5.

In round 3 Leela with black against Fizbo, reached a material imbalanced position but with her King exposed she couldn’t avoid a perpetual check with a draw.
One of Leela’s weak spots is that she is too weak in recognizing perpetual checks that lead to draw, but in this game this wasn’t an issue since it didn’t cost her anything because the position was draw anyway.
Xiphos with white also drew Stockfish.

CCCC continues running and we are on round 3 currently. The level of play is very high as it was expected and interesting games and positions arise.
Shredder is on the lead now with 3 points out of 3 games but other engines can reach that too(Komodo, Houdini).

It’s not completely relevant to Lc0, but many people who follow CCCC wonder how to disable sound.

Test20 is being run for a few hours already, and several people expressed a concern that this time progress is slower then it was in previous runs.

Slower progress at start is expected (per network, not that much per time), for 3 reasons:

Chess.com Computer Chess Championship starts today.

24 engines will participate playing all against all twice, in a double Round Robin tournament with 15 minutes for each player for the game plus 5 seconds per move increment and pondering(thinking in opponent’s time) on. There will be no opening books usage for the 1st round. Every engine will calculate all the moves by itself.
Leela will play on four Tesla V100 GPUs while the other engines on 46 threads of a 2 x Intel Xeon Platinum 8168, 2.70 GHz that has 48 logical cores and 96 threads.

The hardware is very fast, the engines belong to the top ones so the level of play will be amazing.
Every engine will play 46 games so there would be 46 rounds.
After all games are completed, the first 8 of the 24 engines will advance to round 2.