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

Author: Albert Bertilsson

Date: 09:58:53 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
>>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.
Lucky me I didn't have oceans of time to optimize it. Although some time has
been spent on optimization I consider it well spent since it radically improved
my engine. A was happy that I got it right, sadly such a thing doesn't last. My
movegen is currently good enough to be the best part of my engine and I will not
spend time on it any more, I'd rather improve other things, although nowadays I
have almost no time for Sharper =(.

>I found a good post by Bruce Moreland about that, I just can't say it any better
>myself :)

Bruce is a wise man.


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