Author: Bruce Moreland
Date: 10:19:36 08/10/01
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On August 10, 2001 at 06:34:29, Martin Giepmans wrote: >On August 09, 2001 at 12:38:58, Bruce Moreland wrote: > >>On August 09, 2001 at 06:12:52, Martin Giepmans wrote: >>best move is, say, Nc3. Score +0.10. >>> >>>I think this proves your point: drawscores influence other (nonzero) scores. >>>However, along path B white has obviously not played the best moves. >>>If white gets 0.10 instead of 0.40 there must be something wrong with either 2. >>>Nf3 or 1. d4 or both. >>>So, my question is: does this influence of drawscores minimax downto the root of >>>the tree? My first thougth was no, my last (thought 31) is: I really don't know >>>... >> >>The answer is yes, as anyone who has seen the fail-high/fail-low effect in a >>vanilla program with nothing special except hash tables can attest. >> >>This was the subject of one of my first r.g.c.c. posts, in 1994. >> >>bruce > > >What is this? Are you getting irritated? Maybe I'm stubborn but to me it's not No more than usual. It's like 6 days until plane trip, and that won't be fun. >about who is right or wrong. I just want to be sure. And what anyone sees, well, >500 years ago anyone could see that the earth was flat ... >What happens in a search is obviously very complicated. Alfabeta, hashing, >pruning, etc, all these things interact. We try to find our way by a kind of >fuzzy reasoning, mixed with questionable induction from experience. >It's like in the early days of physics or statistics. People often got wrong >results because they had no exact mathematics or controlled experimenting to >rely on. In this situation we have to be very careful. Any conclusion might be >wrong. Do you agree? > >About the weird thing in your vanilla: I've also seen it, but that was >*before* I implemented detection of repetition. It disappeared when I disabled >pruning ... You see, there is the doubt again ... My original version used no pruning of any sort, other than the safe alpha-beta kind. I got this problem when I added repetition testing. Any sort of pruning based upon alpha or beta, and that includes null-move pruning and all that, will lead to this problem as well. Hashing will also cause it if: 1) You get a collision. 2) You cut off based upon the results of deeper searches. All the good stuff makes your search unstable. bruce >Anyway, I understand I will see you in Maastricht, I wish you good luck but of >course I hope I will mate you :) > >Martin
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