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Subject: Re: Null Move and Schizophrenia

Author: Will Singleton

Date: 21:32:46 06/13/99

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On June 14, 1999 at 00:00:46, David Blackman wrote:

>On June 13, 1999 at 21:10:57, Pat King wrote:
>
>>Before implementing null move, I had a simple aspirated AB search, and would
>>research with a window of (Beta, Infinity) for fail highs and (-Inifinity Alpha)
>>for fail lows. And life was good. With null move, however, it's not uncommon for
>>my program to get stuck, alternately failing high and low, without ever properly
>>resolving the score. What's up with that? Must the research be done
>>(-Infinity Infinity)? Or is this a sign that I've a bug in the null move code?
>
>This must be close to the most common technical/programming question on CCC.
>Maybe we need a FAQ? Unless this happens VERY often, the chances are that it's
>not a bug. It's just one of those things that happens with most kinds of
>selective search. Doing a (-inf, +inf) window will eat heaps of time and not
>necessarily get you a more accurate answer. So the best is probably just to
>return some kind of plausible value as soon as you detect the loop starting.


Of course, if you don't use fail-soft, then it never occurs.  I think you can
get away with that by using pvs.

Will



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