The chess Terminators are already among us

Jeff Attwood has an interesting blog which is consistently informative. But occasionally he strays onto subjects that are outside his core expertise. And his recent article on chess and computers is an example of this. As an ex-professional player (albeit a not very successful one), and co-author of a chess program that was quite strong in its day, I think that his analysis of the strength of chess computers is rather superficial. 

Brute force versus AI

Jeff correctly points out that the brute-force approach (type A) has historically been much more successful in producing strong chess computers than the AI-type approach (type B). But he then suggests that type B programs are starting to emerge, and uses a quote from an interesting ExtremeTech article on building a personal computer optimised for playing chess:

"Despite its vastly inferior brute force, the Deep Blitz machine could already be a match for Deep Blue because of improvements in chess software. Deep Fritz is able to evaluate lines of play to a similar depth because it successfully narrows its search only to the strongest lines of play."

In fact, what Deep Fritz is doing here (null-move forward pruning) has nothing to do with an AI-type approach. Instead, it's just a sophisticated tree-search technique that allows you to cut-off large parts of the search tree without actually doing a full analysis. So this is really just a clever addition to the brute-force armoury - it owes absolutely nothing to AI. Fritz and its competitors such as Shredder and the chess monster known as Hydra are basically brute-force searchers with only a rudimentary understanding of chess positions when compared to human grandmasters. 

Will chess computers consistently beat all humans?

I think Jeff is correct in his dismissal of Bram Cohen's ultra-simplistic analysis of the current state of computers versus humans in chess. But he counter-attacks with an old article by chess statistician Jeff Sonas stating that the top 200 humans are (or were in 2001-2003) keeping up with the best chess computers. This article has at least 3 problems: 

  • It's impossible to draw statistically-valid conclusions from just 65 games.
  • 2003 is a long time ago in computer terms.
  • History has shown that Sonas was probably wrong. 

The most significant recent match was in mid-2005 between English GM Michael Adams (then rated number 7 in the world) and the aforementioned Hydra - a chess machine rather than a chess program. Once again, it's not feasible to draw a statistically-valid conclusion from a match of just 6 games. But the result was pretty convincing: 5.5 - 0.5. That is to say Hydra won 5 games and drew 1 game. It's arguable that Adams didn't prepare properly for the match, but it's interesting that Hydra never had a bad position in the whole match. If a human GM can't get to a position that his computer opponent doesn't understand properly, then eventually he's going to be curled up in a corner with his paws pointing skywards. This is because the machines are so strong tactically that it's only a matter of time before the human is caught and pureed.

Here's some commentary from Adams himself on the match:

"I didn't play badly throughout the event, but it’s just so difficult to make an impact. It’s not like playing against other humans – for starters against humans you may actually win a point."

And here is GM Nigel Short's interesting analysis:

"I have a great business proposition for you: I give you $10,000, or $20,000 if you are really, really good. You get on a stage in London and allow yourself to be fucked by a machine for six days. How does it sound?"

GM John Nunn has his own opinion:

"The Adams-Hydra match signals the approaching end of man-machine contests. Already, last year's event in Bilbao was a sign that things were looking bleak for the humans. In Bilbao, it was not so much the performance of Hydra that was so impressive, but Fritz's score of 3.5/4 against Ponomariov, Topalov and Karjakin (twice). Hydra, which made the same score, was running on its special-purpose hardware but Fritz was running on a laptop computer from the local department store."

And if all that doesn't convince you, Vladimir Kramnik has recently retained his world chess champion title, and is due to play a match against Deep Fritz in November 2006. Here's his analysis of his chances against a program that isn't as strong as Hydra:

"Vladimir Kramnik said that Deep Fritz was definitely the favourite and rated his chances for beating the machine at about 40-50%.....The Classical Chess World Champion replied that certainly the day would come when computers would play so well that no human being could compete against them, but that he hoped that November 2006 would not be that day. He believed that the contest between man and machine will still be exciting for a couple of more years."

Wesner Moise adds his own contribution to the debate. It's true that "draw death" may give humans a chance to hold on to their illusions for an extra year or so. But the end is going to be both brutal and inevitable: the machines will prevail - and the chess Terminators are already among us.