Computer Chess Club Archives




Subject: Improvements in BF makes my MoveGen suck =(

Author: Albert Bertilsson

Date: 05:13:53 06/27/03

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

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