Computer Chess Club Archives


Search

Terms

Messages

Subject: Bounds... when is an exact score an EXACT score?

Author: Ross Boyd

Date: 23:33:13 07/31/03


Hi all,

I want to get a clear definition of hash table bounds...

So, this is what I understand...

When we get a score during search, one of 3 things can happen:

1. The score is >= beta... so we store this as a LOW_BOUND.
2. The score is <= alpha... so we store this as a HIGH_BOUND
3. Or its between alpha and beta... so its an EXACT score.

So the definition of an EXACT score is anything we find between alpha and
beta...

So far so good....

Ok, what about an EGTB probe? A successful EGTB probe returns a true score
whether it be a draw or the number of moves to mate.

By applying the 3 rules above I SHOULD store the EGTB score as a LOW, HIGH or an
EXACT bound...  Is that correct?

Why not store it as an EXACT score?  (Its as exact as you're going to get...)
Will the ab search break in some subtle way if I do this?

I'd like to understand this once and for all....

Thanks for your comments!!

Ross







This page took 0 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.