Author: Anthony Cozzie
Date: 10:10:25 08/31/04
Go up one level in this thread
On August 31, 2004 at 04:50:27, Richard Pijl wrote: >On August 30, 2004 at 14:03:49, Dan Honeycutt wrote: > >>In spite of Dr. Hyatt's admonishment that this was a loser in Crafty, I'm bent >>on trying it. Since I do legal move generation I can do the pins for half price >>- I either have or can use the pin data for one side in conjunction with >>generating moves. I just finished the routine. My NPS dropped by just over 4% >>on bench test psitions. I've just started testing an hope to have some >>indication if pin detection is a win, lose or draw in a few days. >> >>One aside - the pin detection is not always more accurate (or mine isn't). In >>the following position for the move Nxg5 the no-pin SEE correctly returns +1 >>where the pin-detection SEE comes back with -2. >> >>[D] 7k/4q3/8/6p1/4N3/5N2/8/4K3 w - - >> >>Fixing this would require keeping track if the pinning piece enters the >>exchange, which I'm afraid would bee too expensive. > >I'm feeding both pinned and pinning pieces as a bitboard to my SEE routine. >Whenever a pinning piece enters the exchange (easy check with bitboards) I'm >examining whether the pinning piece releases a pin, or that another piece >becomes the pinning piece. >Of course, there are positions where this misevaluates as well, but generally it >gives a better value. >The penalty for taking pins into account in the SEE is not that big when you're >already have those bitmasks available for evaluation purposes. >I only use the pin-aware SEE in Qsearch as I don't have the pinned/pinning >bitmasks available in inner nodes (something to try I guess, e.g. to use the >pin/pinning data also in moveordering). > >Richard. Why don't you just call eval at every node? In zappa q-search is 80% of all nodes already (and it will probably hit 90% after my planned q-search changes), so it wouldn't hurt that much, and then you have a lot more information available in your search for better move ordering or pruning. anthony
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