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Subject: Re: Doesn't appear to work for me (full data)

Author: Uri Blass

Date: 12:55:55 11/21/02

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On November 21, 2002 at 09:10:32, Omid David Tabibi wrote:

>On November 21, 2002 at 07:18:11, Uri Blass wrote:
>
>>On November 21, 2002 at 06:26:16, Uri Blass wrote:
>>
>>>On November 21, 2002 at 06:25:17, Uri Blass wrote:
>>>
>>>>On November 21, 2002 at 04:52:13, Omid David Tabibi wrote:
>>>>
>>>>>On November 20, 2002 at 22:05:29, Robert Hyatt wrote:
>>>>>
>>>>>>On November 20, 2002 at 16:55:41, Gian-Carlo Pascutto wrote:
>>>>>>
>>>>>>>Nullmove in Deep Sjeng uses an algorithm of my own, but I can
>>>>>>>switch it back to other systems easily. I did so for running
>>>>>>>a few tests.
>>>>>>>
>>>>>>>I made a version which uses Heinz Adaptive Nullmove Pruning
>>>>>>>and a version which uses your verification nullmove.
>>>>>>
>>>>>>This would seem to be a bit harder than at first glance.  They say that
>>>>>>if the normal null-move search fails high, then do a D-1 regular search
>>>>>>to verify that, but while in that verification search, no further
>>>>>>verification searches are done, meaning that the normal null-move search
>>>>>>fail-high is treated just like we do it today..
>>>>>>
>>>>>>I'm going to experiment with this myself, just for fun, but it seems that you
>>>>>>need to pass some sort of flag down thru the search calls indicating that
>>>>>>you are either below a verification-search node or not so that recursive
>>>>>>verification searches are not done...
>>>>>>
>>>>>
>>>>>Exactly!! (finally someone read the article carefully)
>>>>>
>>>>>See Figure 3 for detailed implementation (the flag you mentioned which is passed
>>>>>down as a parameter for search(), is called 'verify' in the pseudo-code).
>>>>>
>>>>>At first stage leave alone the zugzwang detection part (the piece of code at the
>>>>>bottom of Figure 3). Due to instablilities, some programs might do a needless
>>>>>re-search. First let the algorithm work fine in general, and then do the
>>>>>zugwzang detection part.
>>>>
>>>>I let the algorithm to work without zugwzang detection and first results seems
>>>>not to be good
>>>>
>>>>Some positions I get at the same depth and
>>>>the only position so far in the gcp test suite that I got at smaller depth for
>>>>tactical reasons is
>>>>[D]5rk1/1r1qbnnp/R2p2p1/1p1Pp3/1Pp1P1N1/2P1B1NP/5QP1/5R1K w - - 0 1
>>>>
>>>>I am going to try it in 10 sedconds per move and get resulkts in half an hour.
>>>>
>>>>Uri
>>>
>>>should be seconds,results,position
>>>I type too fast.
>>>
>>>Uri
>>
>>Here are the results of the new version:
>>
>>1     39     39
>>2      9     48
>>3      8     56
>>4     11     67
>>5      6     73
>>6      6     79
>>7      5     84
>>8      4     88
>>9      4     92
>>10      2     94
>>
>>results of the old version seem better:
>>
>>1     40     40
>>2     17     57
>>3      8     65
>>4      7     72
>>5      6     78
>>6      4     82
>>7      8     90
>>8      2     92
>>9      3     95
>>10      1     96
>>
>>Remember also that I tested the olf version at more than 10 seconds per move so
>>if it changed it's mind after 20 seconds from the right move to the wrong move
>>the position is counted as a failure.
>>
>>Uri
>
>Did you use the exact implementation I described in Figure 3?
>
>BTW, you have to compare the algorithms at deeper searches. A fixed 10 ply depth
>will be fine.

Some notes:

I do not the exact implementation in figure 3.
Differences:

1)I do not use null move pruning at depth=1 because I have other pruning and I
did not change it.
null move pruning is used by movei only when the depth is at least 2.

2)I did use research so I have not varaible to tell me about fail high and after
fail high, I trust the result of normal search(verify=false) with depth
that is reduced by 1.

3)I already tested it at 300 seconds per move(still without research) and I
expect to have results tommorow.

I am going to compare it with results of my previous version(null move pruning
R=3)
I use also other pruning ideas that I did not change.

Uri



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