Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: One mate to solve for Champion!

Author: leonid

Date: 10:24:48 06/19/01

Go up one level in this thread


On June 19, 2001 at 13:17:16, Angrim wrote:

>On June 18, 2001 at 19:49:50, leonid wrote:
>
>>On June 18, 2001 at 15:59:36, Heiner Marxen wrote:
>>
>>>On June 18, 2001 at 03:45:49, Angrim wrote:
>>>
>>>>On June 17, 2001 at 16:55:53, Heiner Marxen wrote:
>>>>
>>>>>So let me ask: what is the status of your code?  May we look at it?
>>>>
>>>>My code is private, sorry.  However I would be glad to answer
>>>>questions about how pn^2 works.  I have spent a fair amount of
>>>>time on pn^2 since it is very handy for checking the safety of
>>>>openning lines in suicide chess.  I just had to plug in the
>>>>rules of chess to get a chess mate solver.
>>>
>>>Thanks for your offer!
>>>Next time when I try to understand or implement some sort of pn search,
>>>I will remember it and email you.
>>>
>>>Heiner
>>
>>If somebody between you will explain to me, in genral term, what it is all about
>>(pn search) will be very thankful.
>
>pn-search(proof number search) is a general purpose game tree proving
>heuristic.  I will try to explain it here briefly, but I think that the
>thesis does a better job.
>
>Each node in a search tree is assigned a proof number and a disproof
>number, such that the proof number is the number of leaf nodes of the
>subtree which would need to be proven to prove the root of the subtree,
>and the disproof number is the number which would need to be disproven
>to disprove the root of the subtree.
>At each iteration in the search, it expands a leaf node of the search
>tree which would (if proven true) reduce the proof number of the root, and
>which (if proven false) would reduce the disproof number.  If the leaf
>node is neither proven nor disproven, its proof and disproof numbers are
>calculated, and propagated back through the tree, possibly increasing
>the proof and/or disproof numbers at the root of the tree.
>
>When used for chess, a node is proven if the side to win delivers checkmate,
>and disproven if they are mated.  Draws are a pain in the neck, but can
>generally be scored as having pn and dn of +infinity since a drawn
>position can never be proven to win for either side.  Alternately a
>draw can be scored as a loss for the side that is trying to win,
>which makes things a bit simpler but makes the values asymetric.
>
>>Cheers,
>>Leonid.
>
>Angrim

Thanks for explanation!

Leonid.



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.