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Subject: Re: nullmove and tactics

Author: Johan de Koning

Date: 00:01:12 03/26/04

Go up one level in this thread


On March 26, 2004 at 01:48:18, Dann Corbit wrote:

>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?

I'm not talking about broken (though quite possible) but about ill tuned.

But I think I'm missing your point, if you were making any. :-)
Please followup if you think it's worth it.

... Johan



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