ELF OpenGo

ELF OpenGo is an open-source Go-playing AI created by Facebook. It is based on the AlphaGo Zero approach.

The AI's neural network has been converted to the format used by Leela Zero, and so can be run on that engine. When version 0 was released in May 2018, it was considerably stronger than the standard Leela Zero network, displaying superior positional judgement and sharpness in fighting, but also suffering from problems with ladders. Elf tends to have very strong opinions about positions, giving bigger win rate changes than other bots. Version 1 soon followed, and was notable for preferring black on the empty board, in contrast to other bots such as AlphaGo (Lee, Master and Zero versions), FineArt, and LeelaZero which prefer white with the 7.5 komi. Games played by Elf were incorporated into the Leela Zero training, resulting in its rapid improvement. Leela Zero has since improved and had overtaken Elf v1 by early 2019, but in February 2019 version 2 of Elf OpenGo was released and it's not clear if this is stronger than the latest LeelaZero (with equal playouts of 1600 LeelaZero won 67% of a test match, but with equal time (Elf is only 20 blocks to LeelaZero's 40 so 1 playout on Elf is faster) Elf appears stronger.

Elf weights for LeelaZero engine

• v0: http://zero.sjeng.org/networks/62b5417b64c46976795d10a6741801f15f857e5029681a42d02c9852097df4b9.gz
• v1: http://zero.sjeng.org/networks/d13c40993740cb77d85c838b82c08cc9c3f0fbc7d8c3761366e5d59e8f371cbd.gz
• v2: http://zero.sjeng.org/networks/05dbca157002b9fd618145d22803beae0f7e4015af48ac50f246b9316e315544.gz

Websites

• Homepage: https://facebook.ai/developers/tools/elf-opengo
• Program source code: https://github.com/pytorch/ELF
• Paper: https://arxiv.org/abs/1902.04522
• Analysis of almost 100,000 professional games across history with Elf OpenGo with interactive charts of various metrics such as average winrate loss per move: https://dl.fbaipublicfiles.com/elfopengo/analysis/www/index.html
• Windows binary to play Elf OpenGo (warning: 1.3 GB!): https://dl.fbaipublicfiles.com/elfopengo/play/play_opengo_v2.zip
• iOS deployment and interface through Master of Go program (commercial)