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Subject: Re: how large should a pawn hashtable be?

Author: Dann Corbit

Date: 15:13:25 02/11/04

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On February 11, 2004 at 18:01:44, martin fierz wrote:
[snip]
>hi dann,
>
>i am quite aware that a normal hashtable works as you say - store a key and a
>score. but really, i think that is a much too simplistic view of pawn structure.
>pawns interact with pieces in complex ways, and i basically would like to store
>the information i think important about pawns in the pawn hashtable, to retrieve
>them quickly later. i can also imagine storing a "baseline score" for the given
>pawn configuration. but i really want interactions with pieces too, and as i
>can't hash scores for that, i'd have to save intermediate computations (such as
>connected passers, or potential levers etc) in the pawn hashtable, and then use
>them for the interaction terms.

I bet it will be more expensive to store all that stuff in the hash table and
try to reuse it than to recalulate it.

The best thing about the pawn hash table is that the kings and the pawns move
slowly.  You don't see a ton of rapid change and so a small table gives a lot of
hits.  If you want to store things about rooks backing pawns and other things of
that nature, I think the table will change quickly.  What will you have?  An
ordinary hash table entry.  So why bother with it?

I think the benefits of it will also be less than the benefits of a regular pawn
hash table.  Consider Fine 70.  If you implement all of your machinery in the
hash table, it might not be nearly so useful as a much simpler hash table.

But it would be nice to experiment both ways and find out what works better.

Personally, I would start simple and add things.  If the thing I added made it
slower, I would
#if 0 /* Here is a bad idea that I tried: */
// old code
#endif
around it.



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