Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: nullmove and tactics

Author: Dann Corbit

Date: 22:48:18 03/25/04

Go up one level in this thread


On March 26, 2004 at 01:41:07, Johan de Koning wrote:

>On March 25, 2004 at 19:46:25, Robert Hyatt wrote:
>
>>On March 25, 2004 at 18:10:13, Anthony Cozzie wrote:
>>
>>>On March 25, 2004 at 16:32:09, Robert Hyatt wrote:
>>>
>>>>On March 25, 2004 at 14:28:09, Anthony Cozzie wrote:
>>>>
>>>>>On March 25, 2004 at 13:35:03, Dann Corbit wrote:
>>>>>
>>>>>>On March 25, 2004 at 10:02:57, Anthony Cozzie wrote:
>>>>>>
>>>>>>>On March 23, 2004 at 18:18:51, Uri Blass wrote:
>>>>>>>
>>>>>>>>On March 23, 2004 at 17:28:17, martin fierz wrote:
>>>>>>>>
>>>>>>>>>On March 23, 2004 at 17:13:46, Aivaras Juzvikas wrote:
>>>>>>>>>
>>>>>>>>>>On March 23, 2004 at 16:40:46, Renze Steenhuisen wrote:
>>>>>>>>>>
>>>>>>>>>>>On March 23, 2004 at 16:38:28, Aivaras Juzvikas wrote:
>>>>>>>>>>>
>>>>>>>>>>>>forgot to mention, i dont try null move on 0 ply
>>>>>>>>>>>
>>>>>>>>>>>Than what's your test set?
>>>>>>>>>>
>>>>>>>>>>test set?i just let two versions of my engine play each other a couple of 15 0
>>>>>>>>>>games, the result is either a draw or a win for the one w/o null move, even tho
>>>>>>>>>>it searches deeper as i already mentioned
>>>>>>>>>
>>>>>>>>>"a couple" meaning...?
>>>>>>>>>
>>>>>>>>>if it's two games, forget it. if it's 10 games, forget it too. start believing
>>>>>>>>>it when it's 100 games...
>>>>>>>>
>>>>>>>>I think that if you do not get improvement with null move based on 10 games then
>>>>>>>>there is good chance that you have a bug in the implementation.
>>>>>>>>
>>>>>>>>Uri
>>>>>>>
>>>>>>>I have to agree with Uri here.  If your program plays weaker with null move
>>>>>>>after 10 games, you screwed something up.
>>>>>>>
>>>>>>>Null move is simply _that big_.
>>>>>>>
>>>>>>>Getting 2 extra plys should show up long before 100 games . . .
>>>>>>
>>>>>>I have to disagree with you.  You can implement null move incorrectly and still
>>>>>>score better in ten games.  The reason I say that is because I have seen it.
>>>>>
>>>>>Please do not put words in my mouth. I said "If A then B", which you corrupted
>>>>>to "If !A then !B".
>>>>>
>>>>>I stand by my statement: If you implement null move correctly, it _will_ win a
>>>>>10 game match.  2 ply -> 100 elo -> dominance.  Someone can do the math here on
>>>>>confidence regions, but I'm very sure the version with null move has a 95%
>>>>>chance or better to win.
>>>>>
>>>>>anthony
>>>>
>>>
>>>>Null-move is better, but it is _not_ 200 elo better.  Try it.  Both Bruce and I
>>>>played some of these matches (null on vs null off).  It is more like 50-60 Elo
>>>>improvement.
>>>
>>>I said 100.  200 would indeed be a little much :)  But even 60 elo is a pretty
>>>clear difference; you would definitely notice that in a 10 game match.
>>>
>>>>And it _definitely_ isn't "2 plies".  There is a great difference
>>>>in accuracy between 12 plies no null and 12 plies with null...  You go 2 plies
>>>>deeper, but you don't outplay the no-null opponent like it would outplay itself
>>>>with a 2 ply handicap...
>>>
>>>I do checks in q-search which mitigates this problem somewhat.
>>>
>>>anthony
>>
>>
>>If you do checks in the q-search, your non-null 12 ply search will _still_ kill
>>your null 12 ply search...
>
>Yes, it will win a fair share of the endgames. :-)
>
>But besides that, I think it's wishful thinking.
>Like wishing DB's 11 ply is going to kill Fritz' 14 ply.
>It's not going to happen. Even if DB would be alive and would accept
>the challenge, it still would not be going to happen.
>
>But back to the issue: we're not talking about 12 versus 10 ply here.
>At roughly 100 M nodes / search we're talking about 9 ply full-width
>versus 14 ply full-nulled. Assuming both are reasonable tuned, my money
>is on a 300 Elo difference. That is, in a computer pool. Less against
>humans, more against itself.
>
>Consider it an invitation to you and to Bruce to run more experiments.
>Or at least as an invitation to wonder why that 50-60 Elo improvement
>was quite below expectation.

Suppose that the thing that was broken with null move was the depth reduction
(e.g. it was twice what you wanted with R=4/6 instead of 3/2).  Or some other
strangeness.  Then what sort of result would you expect to see?



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.