Author: Ricardo Gibert
Date: 01:29:46 09/02/02
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On September 02, 2002 at 03:28:54, Gian-Carlo Pascutto wrote: >On September 02, 2002 at 02:19:08, Ricardo Gibert wrote: > >>This isn't clear. Remember the hardware is not searching near the root. It is >>only searching near the leaves. The vast majority of the time, all you may want >>to show near the leaves is if all the "relevant" positions in the subtree are >>greater or less than a certain bound. For this mtd(f) would fit the bill just >>fine despite the absence of a hash table as long as a research does not need to >>be performed. > >But *if* a research needs to be performed, you're looking at an average of >about 10-15 iterations to converge on a new value (true MTD, their bisection >approach is less efficient). Because of the lack of hash, thats a tenfold >overhead. If we assume they have move ordering comparable to current programs, >they needed a research about 1/10 of the time. > >Very very roughly, this means that their searches would take about double the >nodes than they would have with a normal search. In comparison with alpha-beta, with no research, you examine 50% as many nodes. With one research you about break even. With 2 researches, 150% as many, etc. Hsu may be making a good bet by using mtd(f). I don't know the details to know for sure, but the fact that the hardware search is only done near the leaves is significant. Depending on the details, it may be possible to arrange for mtd(f) to almost never perform a research. This I would think depends on the software portion of the search and how it harnesses the hardware portion of the search. > >-- >GCP
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