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Subject: Re: Improvements in BF makes my MoveGen suck =(

Author: Sune Fischer

Date: 17:22:45 06/27/03

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On June 27, 2003 at 20:04:29, Uri Blass wrote:

>>If you are determained to get the fastest possible make move, then that excludes
>>the use of attack tables, this will come back to haunt you in the search and the
>>eval.
>
>And this is also counter productive for perft because if you have fast
>make move then you cannot use attack tables for faster move generation.
>
>I believe that this is the reason that Movei was faster than Sharp in
>calculating perft.

Everything seems counter productive for perfting.
Perft has a really bizare profile, hotspots appear where usually there aren't
any. Perft is simply painting the wrong picture, IMO.

> IMO it's very clear that it makes little sense to optimize a
>>makemove+movegen without considering the remaining program.
>
>I agree but I think that the difference between the things is not big.

Yes I would not be surprised if many roads lead to Rome. :)

>>If I wanted a fast perft I'd only have to optimize my makemove, if I could move
>>the big load into genmove I'd go a lot faster.
>
>
>No
>It is better for you not to make the last ply but only generate legal moves.

Yes, sure for perft. But I don't see a reason to build a long list of moves at
the last ply, where I usually won't be needing them.
I think there are more effective ways of extracting any information one might be
interested in.

> However in a *real* search you
>>don't get to make all the moves you generate, so that means the genmoves would
>>profile-wise be just as important as makemove, perhaps.
>
>In real perft I also do not make most of the moves that I generate so
>you see that for me it is similiar.
>
>Uri

Yes, but you do what you do _not_ because of an optimization in the
makemove+movegen, but because you need this information in the search.

I can see why it would be interesting to have the entire list of moves before
searching the first move. Such a list could certainly help one to decide when to
nullmove and what extensions to use.

-S.



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