Author: Uri Blass
Date: 23:26:58 09/10/01
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On September 10, 2001 at 21:15:38, Dave Gomboc wrote: >On September 10, 2001 at 05:31:18, Uri Blass wrote: > >>No >>If you extend a full ply for every singular move by 0.25 pawn you will never >>finish your search. > >Sorry, Uri, but that's simply not the case. Deep thought needs to refute more than one line in order to get a score of +2 and if the singularity in most of the nodes is only singularity of 0.25 there is no singularity in order to prove the +2 score. > > >>>>I start with the fact that most of the game moves before Bg5 does not seem to be >>>>forced so the depth after Bg5 should be very small. >>> >>>*c5* Be4 *Ra6* Rb1 *f5* *Bc2* Rb7 *Bd8* *g6* >>> >>>The * moves are singular. I only see THREE that are not in >>>this sequence, and in all cases Hiarcs disagreed with the move >>>choices so they may very well not be considered singular by >>>Hiarcs because it does not see that they are singularly better >>>but DT obviously did. >> >>I do not believe that they are singular >> >>Ra6 is only slightly better than Rb8 >>g6 is only slightly better than Nf7 > >They might be only slightly better at shallow depths, but as soon as a >difference is found, the better move will be considered singular. Most >implementations mark "singular" in the hash table and continue to extend it even >if subsequently the gap in score narrows again, to prevent search instability. > >>Note that 29.Rb1 is probably a positional error based on Deep Fritz's opinion >>and black gets more than 0.5 pawn advantage after that move. >> >>The point of starting with Bg5 was to convince people that deep thought could >>not see +2 advantage but it seems that you believe that deep thought was god and >>no number of moves is going to convince you that deep thought could not see it. > >It is quite reasonable for DT2 to reach the positions we are examining in a >search during a tournament game. If you can believe that Junior's search tree >can be three times longer in some lines than in others, why can't you believe >that about DT2? I can believe that it could see 40 plies forward in some lines but 50 plies in lines when many moves do not seem to be singular seem to be impossible. Bf4 after Bg5 Bg7 is not singular for white(Deep Fritz prefers h3) and there are a lot of moves that are not singular and even 13 non singular moves in the main line that is a minority is going to make searching the line impossible from Deep thought's point of view. Uri
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