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Subject: Re: incremental attack tables?

Author: Uri Blass

Date: 03:25:23 05/05/04

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On May 05, 2004 at 06:08:34, Sune Fischer wrote:

>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.

No
They only slow the makemove function.

The result of updating attack tables incrementally is significantly faster
makemove.

When I started and did not update moves incrementally making X moves was
significantly slower than generating 30x moves when most of the time was used
for updating the attack tables.

>
>I'd even say that the move generation is were you take all the penalty for the
>attack tables,

No

see above.

 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.

perft is not about move generating speed.
You can see from my explanation in this post that when I started it was mainly
about make move speed inspite of the fact that I generated significantly more
moves.

Uri



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