Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Hash Tables

Author: Marc

Date: 12:54:18 01/08/99

Go up one level in this thread


On January 08, 1999 at 00:08:41, Robert Hyatt wrote:

>On January 07, 1999 at 23:53:36, James Robertson wrote:
>
>>Hi,
>>I have just started implementing hash tables into my program. Already, I have
>>run into *major* problems. Most of them I can probably fix on my own, but a few
>>I need help with:
>>
>>Problem #1 Out of a search of maybe 700k nodes (counting q-nodes), I will only
>>get maybe 6k positions that the program attempts to enter into the tables! What
>>is a reasonable number of storage attempts for a program during a search of that
>>length?
>>
>
>something is wrong.  Whenever you exit from your recursive search call, you
>should do a HashStore() operation...  not just when you fail high or back up
>a good score, but also when you simply back up alpha because all moves were
>refuted...
>
>
>
>
>>Problem #2 I get tremendously few hits, but that is probably because of problem
>>#1.
>>
>>I figured these would be the best solutions to my problems:
>>
>>Solution #1 Someone posting a simple alpha-beta function somewhere where so I
>>can see where what hash stuff (probes, etc.) goes where.
>>
>>Solution #2 Someone also explaining the above code.
>>
>>Solution #3 Someone speculating on what I might be doing wrong (less crucial).
>>
>>Please help!!
>>James
>
>
>look at _every_ return from your search function.  If there is any path out
>of search, except at the top where you detect a repetition or do a hash lookup
>and get a hit, you need to fix that so that you always store the search result
>before exiting.

Does that include quiescence nodes?  I store all nodes up to depth+1 ply (ie. at
search depth 4, all nodes at ply <= 5 get stored.)  Is it better just to store
*all* nodes?



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.