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

Author: Uri Blass

Date: 08:00:56 06/27/03

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On June 27, 2003 at 10:46:08, Sune Fischer wrote:

>On June 27, 2003 at 08:13:53, Albert Bertilsson wrote:
>
>>Just wanted to share my latest findings and warn you from making the same
>>mistake (or maybe I just point out the obvious).
>>
>>I've always been proud to have a very fast movegen, doing perft calculations
>>very fast. I optimized the movegen alot, and always saw playing strength
>>increasing. I use a legal move generator and always saw the cost of verifying
>>legality to be minor. Lately however I've noticed that the engine performance
>>isn't that great (compared to other engines) inspite of the fast movegen. So I
>>started digging today and the numbers struck me as lightning...
>>
>>As I've improved moveordering very much with hashtable/iterative deepening,
>>killer moves and history tables the effective BF is now much lower. The lower BF
>>now means that very few moves of all the generated ones are actually ever made.
>>This means that the cost of generating legal moves have increased incredibly
>>much.
>>
>>It's really anoying to notice that something you though was very good now is on
>>the list of improvements again =(.
>>
>>/Regards Albert
>
>What that saying with premature optimization being the root of all evil? :)
>
>Well it think it is correct, and probably a typical mistake to spend oceans of
>time optimizing one thing only.

I do not think that the Albert spent ocean of time in optimizing.
Based on reading his posts I got the impression that he did not do it.

His program is relatively fast in perft because his program has a different
structure(he use legal move generator when most of the programmers do not do
it).

Uri



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