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Subject: Re: What is the History table?

Author: Robert Hyatt

Date: 13:33:37 09/17/99

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On September 17, 1999 at 12:18:12, Owen Lyne wrote:

>On September 17, 1999 at 12:07:57, Peter Fendrich wrote:
>
>>On September 16, 1999 at 22:52:42, Robert Hyatt wrote:
>>>First, don't clear the killers, ever.  Second, use them before generating any
>>>moves, after making sure each is a valid move in the current position...
>>
>>Well, I don't clear the killer but the counter is set to 0 in the beginning of
>>each new ply...
>
>Hmm - I'm wondering what Bob means by 'ever' here. For example, I know he likes
>to keep the hash table through a game, some informationm remains useful, rest
>gets overwritten, so no reason to waste time clearing it especially. But with
>killers, does some thing work. I mean, you surely don't want Nxf7+ to remain in
>the killers once both of your knight has been exchanged off? Or perhaps even if
>there is no longer something on f7 to capture (or do killers exclude captures
>and/or checks, are those looked after somewhere else? If so, some of my points
>remian, and some don't ;) Or will a killer than no longer kills get removed
>gradually in the same way old hash does, so there's no point specifically
>clearing it?
>
>Owen


My killer move table only holds two killers.  As a result, knight moves are
replaced almost instantly when the knights are gone...  Also captures are never
placed into my killer tables anyway, as I try captures before killers and the
good captures will already be rejected...

But I _never_ "clear" the killer moves.  I zero their counters so that they
can be replaced easily, but that is all.  But while they are never cleared,
they can certainly be replaced in an instant...



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