----- Original Message -----
From: "Lars Nilsson" <[EMAIL PROTECTED]>
To: "computer-go" <computer-go@computer-go.org>
Sent: Tuesday, November 14, 2006 9:11 PM
Subject: Re: [computer-go] Re: How to improve my minimax speed?
On 11/14/06, Dave Dyer <[EMAIL PROTECTED]> wrote:
Just as a caveat, keep in mind that alpha-beta is only guaranteed
to not affect the result if the rest of your search is completely
deterministic. While that's a good first order approximation to
the truth, it's rarely actually true in anything as complex as
a Go program.
To paraphrase Don Rumsfeld, you alpha-beta prune your tree based on
the evaluations you got, not the evaluations you wish you had. ;)
Lars Nilsson
To put it in another way: AB will find the bad moves faster.
Actually I am in the meantime quite sceptical about the usefullness of AB in
Go. At least for 19x19. In chess AB solves a lot of problems. In Go it
solves some, but it creates a bunch of new ones.
If one has no horizon there is no horizon effect. Pushing up urgent moves
along the variation is another very nasty problems. Who is too move in the
subgames another one.
If the evaluation has some holes, the AB search will find it. In a
conventional Go programm the knowledge based evaluators avoid to a great
deal these holes. The generated positions are much more reasonable/closer to
the starting position than in an AB better searcher which tries out
everything. An can of course introduce also in Alpha-Beta
selective/intelligent move-generators.
Chrilly
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