Author: Christophe Theron
Date: 23:26:05 04/13/04
Go up one level in this thread
On April 14, 2004 at 02:21:41, Christophe Theron wrote:
>On April 14, 2004 at 00:26:34, Eric Oldre wrote:
>
>>After you find the 1st "good" move don't you narrow the alpha beta window so
>>that you don't know how much worse the 2nd move is, only that it is not as good
>>as alpha?
>>
>>Or do you not narrow the window at the root node? that seems like it would
>>greatly expand your search tree.
>>
>>or am i missing something else?
>>
>>
>>On April 14, 2004 at 00:09:24, Robert Hyatt wrote:
>>
>>>Simple idea:
>>>
>>>a move is "easy" and can be made after using less than the planned time limit if
>>>and only if
>>>
>>>1. estimated score for first root move is way higher than the second move. IE
>>>say 2.00 better.
>>>
>>>2. This is a recapture. IE opponent just captured a piece of ours and we are
>>>recapturing on the same square.
>>>
>>>Other types of "easy" moves have higher risk to stop the search early...
>>>
>>>
>>>>
>>>>Thanks,
>>>>Eric Oldre (new chess programmer)
>
>
>
>I think that by "estimated score", Bob means the score returned by a SEE (Static
>Exchange Evaluator), not by a real search.
>
>
>
> Christophe
I would add that you need some kind of logic to tell your search to not stop
early if you suddenly discover that the real score (the score found by a real
search) is much worse than what the SEE expected.
So if you have an obvious recapture you allocate a small amount of time for the
search. But if the search does not confirm that the move is obvious (the score
for that move is not that good, or the best move found by the search is not the
supposed obvious move) you extend the time by falling back to a normal (much
longer) target time in order to see what's going on.
Christophe
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