Author: Gerd Isenberg
Date: 14:03:40 05/19/04
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On May 19, 2004 at 15:40:35, Tom Likens wrote: > >Afternoon all, > >I've been reworking some of the evaluation elements of my engine >and one of the items I wanted to modify is the scoring of pinned >pieces. So with that in mind I thought I'd share some my thoughts >on the subject (and maybe obtain a few new ideas in the process). > >Currently, I'm including this items my pinned pieces evaluator. > >1. If one side is pinning a piece *and* has the right to move, then use > the SEE function to determine if the piece can be profitably captured. Hi Tom, Yes, like other attacked and en prised pieces too. > >2. If a piece is "absolutely" pinned (a Nimzowitsch term) penalize it. > An absolute pinned piece can't move at all (e.g. a knight pinned to > the king by an enemy bishop would be an absolute pin, whereas > a bishop pinned to the king by a queen would not be since the bishop > could move along the diagonal of the pin). In the opening, when a knight on c3 is pinned by a bishop on b4? Quite normal. One should consider distance pinned piece to king and the for instance whether the pinned piece may be attacked by a pawn. And if not whether the pinned piece is defended by a pawn. > >3. If the piece is absolutely pinned and the attacking piece's value is > less than the value of the pinned piece (regardless of who has the > move) penalize the defender a percentage of the difference between > the attacking piece and the pinned piece. > That makes sense. Specially if the pinned side is to move, otherwise it should be handeled by qsearch. >4. If the attacker has a queen/rook, queen/bishop or rook/rook battery > attacking the pinned piece then increase the penalty. > Same is true for other attacks, if you consider batteries in SEE you will implicitly get that. >5. If multiple pieces are pinned increase the penalties. Also if multiple > pieces are pinned then accessed the pinned side some percentage > of the *largest* pinned piece from either 1 or 3 above. May be in conjunction with some king safety properties. As always - carefully with huge values. Cheers, Gerd > >As I mentioned earlier, I'd be interested in how others handle pinned >pieces. I'd also be interested in just hearing thoughts on the above and >if I've missed anything obvious. > >cheers, >--tom
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