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Subject: Re: When to RecordHash()?

Author: Georg v. Zimmermann

Date: 04:11:28 12/26/01

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first I think its not a good idea to call the move stored in your hash entry a
"killer" since killer moves are something different, used by some in move
ordering. It is generally better to explain what exactly you are trying to do
than using "buzz" words in a misleading context.
I realize this sounds unfriednly, but that isnt the intention :).

From your question I guess that you have one search() function that calls itself
recursively in an AB algorithm. And that your main() calls that search() to get
the best move.
It is better IMHO to use one searchRoot() called by main() that calls search()
for all the moves at the root. That will allow some search enhancements.
It will also solve your HT problem, since even when a probe in search() at ply1
returns only a value, but not a move, searchRoot() will know to which move this
value corresponds.


>>If I understand your question, there are three kinds of positions where you
>>can store a hash entry.  PV entry where the score is _EXACT_.  You should
>>have a best move to store hre.
>>LOWER entry which is AKA a fail-high position.  A move caused this fail high
>>and it should be stored in the hash as best.
>>UPPER entry which is AKA a fail-low position.  There is _no_ best move in this
>>position.  I simply store a 0 for such cases...
>Yeah that's what I mean, the first thing i do in the AB search (I'm not using
>PVS yet) is to probe, and if succesful I put the killer into the pv and return
>with the score.
>At the end of the search I expect there to be a move in the pv, namely the best
>move the search could find. What if the entire search is returned from a probe
>hit, one that did not have a move stored, then the pv is empty!
>I hasn't happend to me yet because most entries do have a killer, but it could
>happen I guess.

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