Author: Tord Romstad
Date: 02:35:40 04/14/04
Go up one level in this thread
On April 14, 2004 at 04:57:01, Dann Corbit wrote:
>So my next question is, how do you normally populate a hash table with PV nodes,
>since we only get edge values during the search? Do I need to follow the pv
>from hash to hash with a makemove for each succeeding pv node?
I am not sure exactly what you mean here. Are you asking how you build the PV
beyond the first move? In pseudo code, I do the following:
void build_PV() {
hashentry_t *h;
int i;
for(h=get_hash(CurrentHashKey), i=0; h!=NULL && i<MAX_DEPTH && he->move;
h=get_hash(CurrentHashKey), i++) {
PV[i] = h->move;
hash_make_move(h->move);
}
PV[i] = 0;
}
hash_make_move() is a function which is similar to make_move(), except
that it only updates the hash key.
Note that what you get is not really a PV at all. It is just a string of
moves which all caused a beta cutoff somewhere in the search. It could
be too short, too long, or contain incorrect moves. In Gothmog, it even
happens that it contains illegal moves, because I don't hash en passant
information.
Tord
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