Author: Ricardo Gibert
Date: 23:19:08 09/01/02
Go up one level in this thread
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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