Author: Michael Henderson
Date: 12:20:11 09/23/04
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On September 23, 2004 at 13:14:32, Stan Arts wrote: >Hi > >Today, I've been experimenting with anti-piecetrading again. I have a >preference for Neurosis to try to keep it's pieces, to play more "human"like, >and offer more resistance. > >I've always had a system for this, each new gamemove the computer's pieces >are counted, and in the evaluationfunction the current number of computer's >pieces is compared with this root-count. Then the penalty for each traded >piece is also dependant on how much ahead or behind in general. This seems >to work ok for a single position, and sort of works as expected. But what's >worrying is that this can sometimes give hashtable-instability when re-using >hashscores for next gamemoves, because it's root-dependant. > >So I wonder, what do you do to to solve this problem? Can you invalidate entries in the hash table when a capture is made on the board? > >Do you even use any anti-trade code or none at all? no > >Because there seem to be a few other problems too. >Even with small values, (I was using 0.03 pawn for a light piece, in equal >positions) instead of having a "human"like tendency not to give away it's >pieces, it's going to play very cramped to try and keep it's pieces. (hiding >them away, in dumb ways only a computer can) And is happy to play poor >positional moves, giving away positional advantages by the penalty-ammount >for trading pieces, instead of the effect I wanted. :) So often making weak >moves in quiet positions. >Often expecting the opponent to capture it's pieces. So expecting nonsence >lines. >And asymetry. Although with the system as I described above it's back to 0 >again for each new capture-gamemove. (But with a change in score, which can >give the hashtable-problems.) > >Also, this afternoon I've turned the code off for the first time in a long >time, and to my surprise/shock it really does seem to play a bit better..I >hadn't thought anything of it in a long time. (oops) > >What are your thoughts on this? > >Maybe such code is better left out all together, and values for a piece >being "good" or "bad" and so are much more important anyway? > I think it will play good moves sometimes but it will also play its share of very weak moves...so I think it's best left out. Michael >Greetings >Stan
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