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Subject: bitboard eval question

Author: Kim Roper Jensen

Date: 05:58:13 11/20/02


Hi

I just wondered, if we take an bitboard program and its evaluation function, and
then looked at all the bitmaps used/generated in it how many would be the same
??

What i wanted to know was, if there is any redundancy in the evaluation
bitboards, for example the same bitboard gets generated multiple times but in
different areas of evaluation.

My idea was something like this:

I assume that every evaluation rule is dependant on 1 or more bitboards, so we
can say that a eval rule is dependant on 1 or more bitboards.

Every evaluation rule that is used only 1 time gets scored first.
Every evaluation rule that uses 2 or more bitboards that the first rule has
generated
and so on.

The trick should be that we only generate each bitboard once and then never
again and arrange code so we're using this fact.

simple example with pawn eval:

pawnBitBoard >> 8; all pawn moves 1 forward(or backward dependant on
orientation), but this can also be used to se if a pawn can interpose between an
attacker and defender.

So instead of making clean easy readable code, we evaluate at once when we have
the bitboards that the rule is dependant of.

With regards
Kim

PS If this sounds like rubbish, theres a big chance it is, im not using
bitboards myself but like fiddling with stuff :)

PPS If the start of the first PS is correct please dont flame me, im on work,
tired and almost drugged dead by coffe :)








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