Robot Wars

Twenty years ago, I was an avid fan of the cult TV programme Robot Wars. Teams of contestants would design and nurture their metal offspring, and then set them to fight. The goal of these remote-controlled battles was to cripple the enemy robot, or eject it from the arena. They sliced, bashed, torched, shoved and flipped each other, and much of the fun lay in trying to guess which technique would triumph.

A clash of contrasting styles clearly holds some visceral appeal. Mongoose or cobra? The shackled bear, or the snapping bulldogs? Bearbaiting is consigned to history, but there is an ongoing online dogfight between two of the top chess engines, Stockfish and Leela Chess Zero. Stockfish, an open-source chess engine, is freely available and very powerful. It is a ‘brute force’ engine, in the same tradition as IBM’s famous ‘Deep Blue’ which defeated Garry Kasparov. Leela (sometimes known as Lc0) is the young upstart, a ‘neural net’ engine, which is based upon DeepMind’s famous AlphaZero, which caused such excitement when its games were first published a couple of years ago. (Game Changer, written by Matthew Sadler and Natasha Regan, is an excellent guide).

You can’t run AlphaZero on your own computer, but the revolutionary artificial intelligence algorithms which underpin it were described in detail by DeepMind. They provided a blueprint for Leela, a program which can be run at home, thanks to a distributed online development effort.

‘TCEC’ (Top Computer Engine Championship) (tcec-chess.com) is a regular competition for the world’s best engines, in which Stockfish and Leela have consistently risen to the top. Season 17 ended in April with a narrow 52.5-47.5 victory for Leela over Stockfish in the final. The differing design of these engines leads to some incredible battles.