Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: retrieving the PV from hash questions

Author: Michael Henderson

Date: 19:07:37 09/08/04

Go up one level in this thread


On September 08, 2004 at 19:59:57, Robert Hyatt wrote:

>On September 07, 2004 at 23:56:26, Stuart Cracraft wrote:
>
>>On September 06, 2004 at 22:41:32, Robert Hyatt wrote:
>>
>>>On September 06, 2004 at 22:05:58, Stuart Cracraft wrote:
>>>
>>>>On September 06, 2004 at 18:33:47, Robert Hyatt wrote:
>>>>
>>>>>On September 06, 2004 at 04:47:12, Alessandro Scotti wrote:
>>>>>
>>>>>>On September 05, 2004 at 22:12:35, Stuart Cracraft wrote:
>>>>>>
>>>>>>>I walk the PV until there is no further position. No limit. This can then
>>>>>>>either be left in the hash table if you don't clear between searches
>>>>>>>but like Bob, you should keep the PV entries and restore them in the
>>>>>>>hash table before the next search whether or not you table-clear due to
>>>>>>>potential changes.
>>>>>>>
>>>>>>>I don't do this. It's a simple fix. I don't know why I've delayed putting
>>>>>>>it in.
>>>>>>
>>>>>>I don't either. But since I get my PV from the hash table, it's already there.
>>>>>
>>>>>
>>>>>It won't _always_ be there .  That is the problem.  You can overwrite a key
>>>>>position and lose a move in the PV, and hence the _rest_ of the PV will not be
>>>>>useful.
>>>>
>>>>I understand that. But unless you record the PV with an alternate technique,
>>>>you can't fill it since source == destination.
>>>
>>>I was assuming a non-flawed method of maintaining the PV.  :)
>>>
>>>
>>>
>>>>
>>>>And I am not sure I want to do the triangular array gubbish.
>>>
>>>
>>>That's _the_ answer to do it right, however.  And it is trivial to do.
>>
>>The method I saw at Bruce's webpage doesn't look great to me.
>
>
>In Crafty, it adds 3 lines of code to quiesce.c, and another three lines of code
>to the points in search.c where I return a value other than alpha or beta...

Is he thinking it's slow? because it is not, i have done tests, < 1% speed
change.



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.