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Subject: A few hashing questions.

Author: Severi Salminen

Date: 07:06:56 12/02/01


Hi!

I implemented pawn hashtable to my engine. A good thing is that it works and was
quite easy to program. The bad thing is that my engine just slowed down by 10%
or so. I update the pawn hashkey incrementally during makemove(). The hit rate
is usually over 90% so it is working efficiently. Maybe my engine could benefit
more if the evaluation of pawns was more complex, now I only check for doubled
and isolated pawns, center comtrol and passed pawns. Pawns also affect on open
file evaluation for rooks, that's why I include also rooks in pawnhashkey.

1. Do you update the pawn hashkey incrementally (or decrementally?) also in
unmakemove() or do you use an array of different keys: pawnhashkey[ply]?

2. What pieces do you include in your pawnhashkey? I include all the pawns and
rooks. Adding more pieces might result more stored info to hash table but also
slow the makemove down.

3.-9. Any suggestions or is my result only because my eval() is very simple?

Severi



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