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Subject: Re: incremental attack tables?

Author: Sune Fischer

Date: 03:08:34 05/05/04

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On May 05, 2004 at 05:55:10, Uri Blass wrote:

>On May 05, 2004 at 05:39:28, Sune Fischer wrote:
>
>>
>>>   First you update the attack table with the move and then you generate only
>>>legal moves based on the attack tables , right? What i do is update the attack
>>>table and then generate "pseudo legal" moves,except king moves to an attacked
>>>square. So our difference is you have a routine which calculates only legal
>>>moves based on your attack tables. I don't see how that can speed up perft
>>>immensely.
>>
>>It can't :)
>>The speed up Uri gets in perft comes from not having to make the moves at the
>>leaf.
>>The moves are just generated and then counted and the makemove is saved.
>
>This is the speed improvement relative to other programs but I am talking about
>the speed improvement relative to my initial version and the trick of not making
>the last move was always used by movei.
>
>If you need the attack tables to generate moves then it is clear that updating
>them faster is going to cause a speed improvement.

Attack tables will only slow down move generation, IMO.

I'd even say that the move generation is were you take all the penalty for the
attack tables, but then you hope to get the investment back on improved search
rules and evaluation. SEE should become a lot faster for instance.

When I used them I also generated them incrementally and it was much faster than
from scratch. Like Omid says though, it probably depends on the design.

>My intial version was very slow in calculating perft not only relative to movei
>of today but also relative to Crafty.

I think it's hard to relate perft times with move generation speeds because you
use that trick, comparing Movei and Crafty here would be comparing apples and
oranges.

-S.
>Uri



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