[Humanist] 29.773 AI and Go

Humanist Discussion Group willard.mccarty at mccarty.org.uk
Sat Mar 12 09:02:34 CET 2016

                 Humanist Discussion Group, Vol. 29, No. 773.
            Department of Digital Humanities, King's College London
                Submit to: humanist at lists.digitalhumanities.org

        Date: Fri, 11 Mar 2016 12:17:38 +0000
        From: Willard McCarty <willard.mccarty at mccarty.org.uk>
        Subject: AI and Go

Many here I expect will be interested in "Showdown", in The Economist 
for 12 March, on the simulation of the East Asian board-game by DeepMind 
(https://deepmind.com). The article may be found online at


The author comments,

> The rules of Go are simple and minimal. The players are Black and
> White, each provided with a bowl of stones of the appropriate colour.
> Black starts. Players take turns to place a stone on any unoccupied
> intersection of a 19x19 grid of vertical and horizontal lines. The
> aim is to use the stones to claim territory....
> This simplicity, though, is deceptive. In a truly simple game, like
> noughts and crosses, every possible outcome, all the way to the end
> of a game, can be calculated.... The most complex game to be “solved”
> this way is draughts, in which around 1020 (a hundred billion
> billion) different matches are possible. In 2007, after 18 years of
> effort, researchers announced that they had come up with a provably
> optimum strategy.
> But a draughts board is only 8x8. A Go board's size means that the
> number of games that can be played on it is enormous: a
> rough-and-ready guess gives around 10**170. Analogies fail when
> trying to describe such a number. It is nearly a hundred of orders of
> magnitude more than the number of atoms in the observable universe,
> which is somewhere in the region of 10**80. Any one of Go’s hundreds
> of turns has about 250 possible legal moves, a number called the
> branching factor. Choosing any of those will throw up another 250
> possible moves, and so on until the game ends. As Demis Hassabis, one
> of DeepMind's founders, observes, all this means that Go is
> impervious to attack by mathematical brute force.
> But there is more to the game’s difficulty than that. Though the
> small board and comparatively restrictive rules of chess mean there
> are only around 10**47 different possible games, and its branching
> factor is only 35, that does, in practice, mean chess is also
> unsolvable in the way that draughts has been solved. Instead, chess
> programs filter their options as they go along, selecting
> promising-looking moves and reserving their number-crunching prowess
> for the simulation of the thousands of outcomes that flow from those
> chosen few.....
> Working out who is winning in Go is much harder, says Dr Hassabis. A
> stone's value comes only from its location relative to the other
> stones on the board, which changes with every move. ....


Willard McCarty (www.mccarty.org.uk/), Professor, Department of Digital
Humanities, King's College London, and Digital Humanities Research
Group, Western Sydney University

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