Author: Don Dailey
Date: 14:19:56 11/02/98
Go up one level in this thread
On November 02, 1998 at 04:49:55, Ernst A. Heinz wrote: >On November 01, 1998 at 23:46:42, Robert Hyatt wrote: >> >>On November 01, 1998 at 13:47:18, Ernst A. Heinz wrote: >> >>>On November 01, 1998 at 12:56:12, Inmann Werner wrote: >>>> >>>>you are right. my percentage is about 50% in normal game. I have to think about >>>>it. >>>>On the one hand, if I make a hit, the evaluation is extremly fast. On the other >>>>hand, if I only hash the pawns, I get much more hits, but have more to do in >>>>much more difficult in evaluation, because good king standing and rook standing >>>>depends on pawn structure. >>>>When I have a little time, I try both and look whats really faster. >>> >>>Werner, >>> >>>All pieces that tend to move around *frequently* will greatly hurt the hit rate >>>of your Pawn hashing. Therefore, I recommend that you never include any major >>>or minor pieces therein. The Kings, however, are different "animals" which can >>>safely be hashed together with the Pawns as long as they must stay behind safe >>>shelters in the middlegame. "DarkThought" drops them from the Pawn hashing >>>*dynamically* as soon as King safety does not matter anymore. >>> >>>=Ernst= >> >> >>I did this in Cray Blitz, but believe that the current scheme I use in Crafty >>is far better. With the king included my hash hits were in the 90% range or >>so, while with it out, 99.9% is common. I looked at what I was doing, and >>it was mainly king safety related. And the king safety with the king at g1 >>is no better/worse than the king safety with the king at h1 or h2, if you only >>look at pawns. I now do normal pawn scoring, then king safety on *both* sides >>of the board, and store all this with just the pawn hash signature. When I >want >>to evaluate king safety, I look at which side the king is on and start with >that >>raw pawn structure score around the king... and then factor in other things >>(like is there a queen, how close are the pieces, are there open files with >>rooks on them around the king) and so forth.. >> >>I now get 99.9% hash hits which covers the king safety pawn structure... and >>there's no loss in accuracy of any kind... > >We must be doing something right then because we also get more than 99% >hit rates with the King factored in. :-) > >=Ernst= Hi Ernst, I think you are measuring something wrong. When you factor in the kings, you should get a significantly lower hit rate. Do the test by clearing the table before every move and in the early middlegame and see what happens. I would like to see numbers with and without if it's not a big hassle for you. What I do is more like Bobs technique, in fact my pawn structure hashing does not even compute pawns structure scores but instead returns lots of useful information to make extracting the scores and many other piece interactions with pawns easy. - Don
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