Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Null-Move: Difference between R = 2 and R = 3 in action

Author: Ricardo Gibert

Date: 19:15:31 07/19/02

Go up one level in this thread


On July 19, 2002 at 21:43:40, Robert Hyatt wrote:

>On July 19, 2002 at 15:50:44, Uri Blass wrote:
>
>>On July 19, 2002 at 15:25:48, Christophe Theron wrote:
>>
>>>On July 18, 2002 at 12:14:10, Robert Hyatt wrote:
>>>
>>>>On July 18, 2002 at 05:58:56, Vincent Diepeveen wrote:
>>>>
>>>>>On July 17, 2002 at 13:18:40, Christophe Theron wrote:
>>>>>
>>>>>>On July 16, 2002 at 11:01:23, Vincent Diepeveen wrote:
>>>>>>
>>>>>>>On July 15, 2002 at 13:11:09, Christophe Theron wrote:
>>>>>>>
>>>>>>>>On July 15, 2002 at 08:37:34, Omid David wrote:
>>>>>>>>
>>>>>>>>>I don't think using double null-move is a good idea in practice, since in
>>>>>>>>>midgame the chance of zugzwang is negligible and thus it's superfluous (I doubt
>>>>>>>>>if even DIEP uses it). However the contribution of double null-move is that it
>>>>>>>>>gives legitimacy to the null-move pruning idea, proving that it _is_ a correct
>>>>>>>>>search method (anyway, no one doubts null-move nowadays).
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>Why does double null move prove that null move is a correct search method????
>>>>>>>>
>>>>>>>>Doing two null moves in a row means going back to standard search (a search not
>>>>>>>>involving an illegal move like null move is).
>>>>>>>>
>>>>>>>>I fail to see how it legitimates null move.
>>>>>>>
>>>>>>>Double nullmove legitimates (duh can't you use easier to spell words)
>>>>>>>itself, for the obvious reason that it is provable now that a search
>>>>>>>depth of n ply, where i may pick n, is going to solve any problem you
>>>>>>>give it.
>>>>>>
>>>>>>
>>>>>>
>>>>>>OK, I see now.
>>>>>>
>>>>>>However, it is not true.
>>>>>>
>>>>>>Due to a nasty interaction with the hash table algorithms, just allowing 2 null
>>>>>>moves in a row will NOT solve any problem.
>>>>>
>>>>>What you refer to is a practical impossibility (assuming you have
>>>>>a efficient search) :
>>>>>
>>>>>  your assumption is that from a root position r
>>>>>  with transition of some moves to position p, side stm to move and
>>>>>  depthleft=d:
>>>>>
>>>>>  r ==> p(stm,d)
>>>>>
>>>>>  that you visit this position with properties that
>>>>>  before this move you have made 1 nullmove or less.
>>>>>
>>>>>  so ==> r , nullmove , p
>>>>>
>>>>>  Now a major problem for such an event to occur is that
>>>>>  after 1 nullmove, sides change the side to move.
>>>>
>>>>Why is this a problem?  IE in my case, position P reached thru a path
>>>>with a null-move and position P reached thru a path without null-move
>>>>are _unique_ positions...
>>>
>>>
>>>
>>>If so, your programs loses a lot of opportunities to prune because it detects
>>>less transpositions. But maybe it avoids some problems and is benefical in the
>>>end, I do not know.
>>
>>How much do programs earn by pruning based on hash tables?
>>
>>Today I do not use hash tables to prune the tree.
>>I am interested to know how much rating programs earn from
>>using hash tables to prune the tree.
>>
>>1)Did someone do the experiment of comparing the rating of
>>a chess program when hash tables are used only for things like order
>>of moves and the rating of the same program when hash tables are used also for
>>also to prune the tree.
>>
>>2)How much speed improvement do programs get in middle game
>>from pruning based on hash tables?
>>
>>Uri
>
>
>Try position fine 70 with and without.  Without you might get to depth 15
>or so.  With it you can reach depth 40.  A _significant_ gain...

You're trying to drive Uri crazy aren't you?

Did you really think Uri could not think of an example of a position where
having hash tables makes a significant difference?

Do you really think being able to search a position like Fine 70 to a depth of
40 instead of 15 will make a difference in a programs playing strength?

Don't you realize people are liable to react to such a reply as yours above as a
troll?

Please try to be a bit more thoughtful.




This page took 0.19 seconds to execute

Last modified: Thu, 07 Jul 11 08:48:38 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.