Leela

Leela is a Go playing program by Gian-Carlo Pascutto, author of the strong chess program Sjeng. As of May 2016, the website states that Leela plays at the 4 dan level on a 19x19 board, and at a high dan level on a 9x9 board. The full version is now free.

Leela should not be confused with the more recent, stronger bot Leela Zero; the names are similar only due to having the same lead author, but they play quite differently.

Table of contents Features Implementation Strengths Weaknesses Online versions Comment Remarks

Features

• At 9x9, her strength is around 1 dan ( https://www.britgo.org/junior/improve)
• board sizes 9x9 up to 37x37
• rated games on 9x9 and 19x19 board
• handicap up to 100 stones
• auto adjust (rated games) or preset playing level
• engine games on up to 37x37-board (25x25 for version 0.7.0)
• show territory, show moyo
• analyze mode
• plays always with komi x.5
• asymmetric time settings possible (free games)
• switch sides (by menu "Game" - "Force computer move")

Implementation

According to its web site, Leela is a mix of different approaches. It seems to use a Monte Carlo engine and Deep Learning.

Strengths

• Like other Monte Carlo programs, it performs well against traditional Go programs.
• Leela likes to make a large moyo in the center, which often compensates for the opponent having all four corners.
• Leela often finds interesting moves that really annoy its opponent, and I'm not sure yet whether these moves are tesujis or aji keshi.
• In the opening, Leela often plays a shoulder hit, even against a stone on a hoshi. After doing this in some corners, these stones form a large but loose center moyo. If the opponent misses the chance to invade, this moyo becomes the winning factor.
• Especially in the opening, Leela often plays moves that single-digit kyus want to answer, for example attaching at weak stones or enclosing a group in a corner. This means that Leela can often control what's happening on the board.
• At any point of time, Leela has a good estimate of counting points, which may even allow abandoning a large group.

Weaknesses

• Leela likes to play long sequences of ataris. Against weaker players this often works, but stronger players can easily beat the engine by playing solidly.
• Like GNU Go, its impression about the status of groups isn't always correct, and sometimes it just misses to save a large group from being killed.
• If you're a single-digit kyu player, you may try taking all four corners and then destroying Leela's center moyo. Just take care that the moyo border doesn't become water-proof. This works well for me.
• Programmed to win by few points, she did not play best endgame and may stupidly fill own space to reduce the wining score.
• She did not count the final results in term of points ahead.
• She can be shocked by a good strategic move.
• She does not accept an integer Komi.
• She regards some moves as the best moves but actually they are not.
• She cannot learn and improve her skill from her previous games.

Online versions

Leela is playing 19x19 games on DragonGoServer. It runs with a thinking time of 1 minute without GPU support. It's strength there is 5 dan. Last Update: July 2020.

• Leela v 0.11.0

Comment

moved to Playing Monte Carlo Programs

Remarks

• [1] The cut down version Leela-Lite can be downloaded and used for free
• [2] The development version named LeelaBot? has attained a KGS rank of 6 dan as of mid 2017.