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Stockfish problem in Scid
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Eelco de Groot



Joined: 12 Mar 2006
Posts: 2595
Location: Groningen
PostPost subject: Re: Stockfish problem in Scid    Posted: Sat Mar 17, 2012 6:08 pm Reply to topic Reply with quote
mcostalba wrote:
Eelco de Groot wrote:
I am not sure it is going to matter much but it turns out the exception search can, also in Stockfish, return a ss->currentMove that is identical to the ttMove (or to move).


So what ?

I don't see any problem in setting ss->currentMove at that point. You have added additional, not needed, code just to 'fix' a non-issue IMO.


Hello Marco,

Maybe I just don't understand the code or for that matter your codechange retiring ss->bestMove, but what I thought happened there is a beta cutoff of the exclusion search, ss->currentMove can only be interpreted as ss->bestMove if there was an actual beta cutoff but I assume that was the case. Now because of the cutoff there will be no singular extension awarded, because of I think a hash hit (assuming it is always a hashhit that causes this). The ss->bestMove/ss->currentMove and the triggered assert indicates the move causing the beta cut off was identical to the move that should have been excluded from the search. The excluded move only came back in again because there was no check of the hash content comparing the ttMove found within the exclusion search with the move that should be excluded. It is not a big deal but it seems to me it defeats the purpose of doing an exclusion search when this happens. Or am I totally missing what is happening?

In the old code I called ss->bestMove returned by the exclusion search nexbestMove and used it later on. Not with much succes sofar though. But I never actually tested the assert I had made before. I did not think it was likely to happen, because the exclusion Pos key would always have returned a result from the exclusion search in the position, not the regular search. But it does not seem to be entirely watertight. Only once in an eleven ply search but it still happens...

Regards, Eelco
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Display posts from previous:   
Subject Author Date/Time
Stockfish problem in Scid Marek Soszynski Sun Mar 11, 2012 9:49 pm
      Re: Stockfish problem in Scid Marco Costalba Sun Mar 11, 2012 10:12 pm
            Re: Stockfish problem in Scid Marek Soszynski Sun Mar 11, 2012 10:30 pm
      Re: Stockfish problem in Scid Justin Sherron Mon Mar 12, 2012 12:40 am
            Re: Stockfish problem in Scid Marek Soszynski Fri Mar 16, 2012 7:26 am
                  Re: Stockfish problem in Scid Justin Sherron Fri Mar 16, 2012 10:04 pm
                        Re: Stockfish problem in Scid Marek Soszynski Fri Mar 16, 2012 10:28 pm
                              Re: Stockfish problem in Scid Justin Sherron Sat Mar 17, 2012 11:41 pm
                                    Re: Stockfish problem in Scid Marek Soszynski Sun Mar 18, 2012 5:57 am
      Re: Stockfish problem in Scid Ignacio Garcia Mon Mar 12, 2012 12:48 am
      Re: Stockfish problem in Scid Steven Atkinson Sat Mar 17, 2012 6:07 am
            Re: Stockfish problem in Scid Marek Soszynski Sat Mar 17, 2012 7:49 am
            Re: Stockfish problem in Scid Marco Costalba Sat Mar 17, 2012 9:39 am
                  Re: Stockfish problem in Scid Steven Atkinson Sat Mar 17, 2012 11:44 am
                  Re: Stockfish problem in Scid Eelco de Groot Sat Mar 17, 2012 2:46 pm
                        Re: Stockfish problem in Scid Eelco de Groot Sat Mar 17, 2012 3:10 pm
                        Re: Stockfish problem in Scid Marco Costalba Sat Mar 17, 2012 5:33 pm
                              Re: Stockfish problem in Scid Eelco de Groot Sat Mar 17, 2012 6:08 pm
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