Author: Dan Honeycutt
Date: 16:55:39 08/31/04
Go up one level in this thread
On August 31, 2004 at 14:30:03, Gerd Isenberg wrote: >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. > Right. My no-pin SEE doesn't know the knight is pinned, my pin-aware SEE doesn't realize the pin is broken. >> >>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. > I'd figure pinned on opposite side = worse than pinned on own side and attakable by enemy pawn = very serious. Not clear on distance to the king - is it worse if farther away? (I'm thinking of the opening where knights close to the king routinely get pinned, most of which are pretty penny-anty) >> >>Doing pin-aware SEE only in QSearch makes a lot of sense. I hadn't thought of >>that. > >Why? > Why what? Why it makes sense: In normal search a good move may get ordered lower do to a bad SEE but I'll still find it. In QSearch it may get discarded. Why I hadn't thought of it: What can I say? Age. Too many cobwebs where there should be electrical activity. Best. Dan H. >Cheers, >Gerd > >> >>Thanks again. >>Dan H.
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