Computer Chess Club Archives


Search

Terms

Messages

Subject: More Hash Table Questions

Author: William Bryant

Date: 21:54:47 01/23/99


Thanks in advance.

These specific questions have not been discussed recently her, or else I
missed the questions and responses.

1. At the root (ply = initialply), you should not probe the hash table at the
start of the search.  (source: crafty SearchRoot).

Is it OK to start probing the table at the first ply beyond the root?

Although not probing the table at the root, do you back up you score and best
move when exiting the root search? I would think so, because this is where
draft will be the deepest as you exit the search.

2. I don't yet have an opening book, and start searching on move one.  The
first implementation of my hash table began to significantly reduce search
time when the iteration reached 7 and 8, but the nodes per second didn't
change.  I am assuming this is due to the fact that the hash table is causing a
cutoff and decreasing the number of nodes searched. Note: my search is to a
fixed depth at present.

Is this expected behavior?
Should I see an increase in the NPS?
(in the opening phase of the game)?

3. Any suggestions for common pitfalls in the implementation of a hash table
that
I should seek out.  I think I've done this right.
The score and move are no different from my fixed search without the hash table,
but the PV moves at deeper plies are in a different order than from before.

Any comment or suggestions would also be appreciated.

William
wbryant@ix.netcom.com




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.