Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Help on hash tables.

Author: Tom Kerrigan

Date: 15:06:30 01/13/00

Go up one level in this thread


I can't point you towards resources, but this is what you should store in each
entry of your hash table:

1) the "unique" (Zorbist, sp?) number of the position
2) the score of the position
3) what kind of score (2) is: alpha, beta, or exact
4) the depth of search that produced the score (2)
5) the best move for the position

As for "deleting/refreshing entries", the algorithm that does this is called the
replacement algorithm. The popular thing to do these days is really to have two
hash tables. In one hash table, you always replace the entires. In the other
hash table, you replace the entry only if it has a lower depth.

-Tom

On January 13, 2000 at 17:06:44, Marco Grella wrote:

>Hello to everybody,
>could someone tell me where I can find something (books or internet resources)
>about the use of hash tables in chess programming? And about good and suitable
>hash functions? I have implemented a transposition table in my (still minimal)
>chess program, but I did it in a quite elementary way  and I think I am going
>to change lots of things (for efficiency reasons and because if I want to
>implement algorithms such as MTD(f) I have to). I think I don't have still
>understood *what* you have better put in your hash table, and *when* you have to
>delete/refresh it.
>Ok, I can look what was done in programs like Crafty, but if you could tell me
>something more...
>Tanks in advance,
>Marco Grella



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.