Author: Vincent Diepeveen
Date: 16:54:20 09/02/02
Go up one level in this thread
On September 02, 2002 at 02:19:08, Ricardo Gibert wrote: without hashtable you can put mtd in the toilet. >On September 01, 2002 at 13:41:19, Gian-Carlo Pascutto wrote: > >>On September 01, 2002 at 13:28:20, Robert Hyatt wrote: >> >>>On September 01, 2002 at 03:20:20, Gian-Carlo Pascutto wrote: >>> >>>>On August 31, 2002 at 23:54:31, Robert Hyatt wrote: >>>> >>>>>Interesting question. Deep Blue essentially used it in the chess hardware, >>>>>which means the last software ply was a sort of mtd(f) search. >>>> >>>>Except that it was missing the 'm' in mtd(f), which made it horribly >>>>inefficient. >>>> >>>>-- >>>>GCP >>> >>> >>>I don't agree. They simply had a piece of hardware that could search a >>>null-window tree, and nothing else. Which is all a single search in a single >>>iteration of mtd(f) can do. The software provided the "m" at the point where >>>the software handed things off to the hardware... >> >>Nonsense. The point of MTD is to use a hashtable to prevent wasted work when >>researching the tree and trying to converge on a value. The Deep Blue chess >>chips did *not* have hashtables. This makes them horribly inefficient, as anyone >>that has actually used or uses MTD will tell you. > >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. Whether or not it is really inefficient depends on how it is used. >However, you are right that "mtd(f)" is something of a misnomer as the "m" is >missing as you have noted. > >> >>The fact that the software part of their search had hashtables has *nothing* to >>do with this. >> >>-- >>GCP
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