Re: [computer-go] A superko paradox

[Heikki Levanto <heikki@xxxxxx>]

On Fri, Feb 11, 2005 at 09:25:31AM -0800, Peter Drake wrote:
> While most ko detections are easy (if this point has never been 
> captured, playing here can't violate ko), I occasionally have to check 
> if the current configuration has occurred before.  While most of these 
> checks are quick Zobrist hash comparisons, occasionally two positions 
> will hash to the same value.  Thus, I have to store the entire board 
> configuration with each move.  This is a frequent, expensive operation 
> to deal with a situation that is very rare, but can happen.
> 
> Is there any way out of this?

Hashing has already been discussed, so I ignore that.

You can at least sort the previous positions in 361 buckets by the
number of stones on board, and check only against the right bucket. Most
buckets will contain only one position.

Doesn't speed up the storing of them, but if you need to check for
repetition, it will be faster.

-H


-- 
Heikki Levanto   "In Murphy We Turst"     heikki (at) lsd (dot) dk

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