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Subject: Re: hash table & draw detection

Author: Uri Blass

Date: 11:52:22 05/02/02

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On May 02, 2002 at 11:48:59, Robert Hyatt wrote:


<snipped>
>It doesn't.  Here is a better explanation...
>
>
>
>root----------YYY----------------------XXX--------------TIP
>
>root-------------------XXX-----------------YYY----------------XXX-------TIP
>
>You search the first path first.  And when you finish searching position
>YYY, you store a score of +1.2...  Which represents what happens between YYY
>and the TIP position.
>
>You search the second path next.  When you reach position YYY you retrieve
>that +1.2 score and use it.  It is _wrong_.  Because position XXX will be
>reached before the tip position is reached, producing a correct score of
>draw.  But you are claiming +1.2 which is wrong...

The only way to use hash tables without these problems seems to be to store
a score for yyy in the hash tables only in cases that the last move before yyy
is a conversion and to look at hash tables in order to cut the tree only after
conversions(you can only use hash tables not after conversions but in this case
using hash tables should be done only for better order of moves and not to cut
the tree).

I do not say that it is a good idea but if someone wants to avoid the errors and
still use hash tables then it seems to be the only way.

Uri



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