Author: Adrien Regimbald
Date: 01:51:23 06/24/00
Go up one level in this thread
Hi,
>Yes. Once it knows things are bad, it is willing to burn time to improve things
>if possible. I see at _least_ one move in every game where this happens, and
>had it stopped with the bad move it would have lost, while searching longer
>restored the game to equality or whatever...
>
>Once you _know_ things are bad, that is the time to use more time and try to
>search for a solution. Of course, once you finish the current iteration, it is
>debatable whether you should go even deeper, since no moves led to a decent
>score.
Hmm.. I'm trying to think of a simple algorithm, that will hopefully improve
things in the majority of cases.. how about something like this (variable names
used to make everything as clear as possible):
/* do we have a significant drop in our score? */
if (root_score + 40 <= last_iteration_score) {
/* are we likely to run out of time on this search? */
if (time_used >= 0.5 * allocated_time && allow_more_time) {
/* can we afford to add extra time? */
if (time_left >= 4 * allocated_time) {
allocated_time *= 2; /* give some extra time */
allow_more_time = FALSE; /* only allow extra time once */
}
}
}
I know that this isn't terribly sophisticated, but I think it will likely work
in a large percentage of cases. Does this seem reasonable? Does anyone have a
relatively simple scheme which handles this issue?
>One 20-year-old trick: When time runs out, _never_ stop searching until the
>current move you are searching has been completed. Most of the time, this
>happens almost instantly. But on occasion, you are ggoing to find a new best
>move, if you have time. Take the time to see.
Hmm, I think I tried this once before, and it seemed very risky to me. It ran
into all sorts of trouble when there were say 2 or 3 moves which gave very
similar scores, and the PV score is only say 5-10 centipawns better than the
other choices..
>That's exactly how a "human" plays chess. :)
Human.. what's that? :P
Adrien.
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