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Subject: questions about pawn hashtable

Author: scott farrell

Date: 19:48:01 06/21/03


I have had pawn hashtables for sometime, here is what I currently hash:

- pawns
- castling rights

I store:
- score
- pawnattacks (my engine is bitboard based, so this is a bit board for
sidetomove)

This is fine for pawn only eval, passed, connected passed, doubled, etc etc. And
if you take these pawn-only scenarios, I get 99% hash hit, and no collisions
(more or less).

My question goes to when you need to include other factors to score pawns
effectively, like:
- the king position and amount of other material for passed pawn races
- the king position for passed pawns, if the king can protect the passed pawn,
then it is more valuable.

Now if you dont hash the "other info" like King position, I assume you have a
nice new bug. If you do hash it, it ends up storing more info, and slowing, more
collisions and less hits in % terms, and the incremental hashkey generation
becomes more complex each time.

What do other people do?

Do you put king protecting passedpawns in the evalKing routine instead?

What about passed pawn races? Do you try to put that in evalking?



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