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Subject: Re: Can we use hash table at root?

Author: Vincent Diepeveen

Date: 16:42:37 01/31/00

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On January 31, 2000 at 16:48:41, Tim wrote:

>Crafty does not use(store and probe) hash table at root.
>How about other programs?
>Is there problem to use hash table at root?

It depends upon how you write to hashtable,
but in general spoken it is not possible.

Suppose you get to the same position as the root position somewhre in
your lines, which is very likely. now suppose one day that's with
difference alfa and beta values, so even though you already have it
in the hashtable you might overwrite it with a small depth, say 1 ply.

then you need to abort your search. searching PV of this ply is not ready
yet. In your hashtable is only a 1 ply search from this position.

Bad luck. all those plies searched for nothing...

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