Author: Don Dailey
Date: 11:10:44 02/08/98
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Hi Bob, >it was "debunked" because of hardware issues. Chess 4.6 searched 6 >plies >full-width on a cyber 176. Mac Hack could barely search 5 plies, with >no >q-search, using severely tapered forward pruning, because of hardware >speeds >in the 60's... IE Greenblatt couldn't even do a 2 ply search full-width >at those speeds. > >What selectivity is all about is being careful at the root by going >full- >width, and taking risks farther out in the tree where you believe that >even >if you make a mistake, you have time to catch it in the full width part >of >the search next time and "fix" it. > >It's a trade-off... do you want to find deeper tactical things? Or do >you >want to find deeper positonal things? Selectivity overlooks things. No >way to avoid it. Question is, does what it find offset what it >overlooks? >Good question. But your estimate of +100 is simply a wild guess. I'd >suspect that a good brute-force program will play just as well as a good >selective searcher. They will each find things the other overlooks. >The >selective searcher will find deeper things, the full-width searcher will >find things the selective searcher pruned away in error. > >Take your pick. I tend to err on the side of simpler algorithms... >fewer >bugs means more wins... You need to expand on your statement that a good brute-force program will play just as well as a good selective searcher. I don't agree with this unless you are talking semantics (like calling Richard Langs program full width because he does a few full width plys.) Marty's program may be the closest thing among the really strong ones but I think he just put's all the selectivity in the quies search. - Don
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