Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Is improvement from hash tables in middle game linear or exponential?

Author: Russell Reagan

Date: 23:20:33 12/19/03

Go up one level in this thread


On December 19, 2003 at 22:05:11, Dann Corbit wrote:

>You can make too large of a hash table if you clear hash frequently (e.g.
>between moves) and the hash clear time becomes significant.

You could avoid this by adding a counter element to each hash table entry. If
the counter of the hash entry is equal to the counter value representing the
"current" search, then that entry is from the current search. Otherwise, it's
old data. You increment the counter after each game move is made (not each
search move). You just have to make sure your counter will last long enough.
Probably a byte will do (256 plies have to pass before an old element could be
considered current).

If your choices are to use a small hash size (say, 32 MB) because you need to
clear it, or use a larger hash size (say, 1 GB) and "waste" one byte per entry,
you'll probably come out way ahead on the amount of data you can store in your
table.



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.