Author: Gerd Isenberg
Date: 11:30:03 08/31/04
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On August 31, 2004 at 12:03:13, Dan Honeycutt wrote: >On August 31, 2004 at 04:50:27, Richard Pijl wrote: > >> >>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. > >Thanks Richard for the good ideas. I'm using my move generation pin routine >which produces a bitmap of pinned pieces and for each one the squares where they >can go - a ray from the friendly king to and including the pinning piece. So >right now I don't have the pinning piece but I can get it pretty cheap. I'll >tinker with this. Hi Dan, sorry for my confusing answer, i didn't got the point. I thought it had something to do with traversing order of the knights in your implementation. Thanks to Richard i'll hope i have it now ;-) Your SEE-routine didn't recognize after Nxg5 Qxg5 the released pin and is therefore to "pessimistic". Richards idea seems quite fine, even not perfect it works in an "optimistic" way. > >Having pins for both sides available at all times opens the door for me to add >pins to my evaluation for no extra cost. Do you just add a bonus per pin or do >you try to make some determination of the worth of the pin? Some possible heuristics: pinned on own or opposite side of the board, distance to own king, attackable by enemy pawn considering own guard pawn, if not, defended by pawn or considering SEE-like attacker and defender. > >Doing pin-aware SEE only in QSearch makes a lot of sense. I hadn't thought of >that. Why? Cheers, Gerd > >Thanks again. >Dan H.
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