Author: Ricardo Gibert
Date: 17:39:58 06/17/05
Go up one level in this thread
On June 17, 2005 at 18:56:08, Vincent Diepeveen wrote: >On June 16, 2005 at 18:42:44, Vasik Rajlich wrote: > >>On June 16, 2005 at 13:31:39, Vincent Diepeveen wrote: >> >>>On June 16, 2005 at 05:22:26, Vasik Rajlich wrote: >>> >>>>On June 15, 2005 at 22:40:22, Tor Alexander Lattimore wrote: >>>> >>>>>Hi >>>>>Is it possible to use a single variable in the MTD(f) search? Something like >>>>>this: >>>>> >>>>>int MTD(int depth, int guess) >>>>>{ >>>>> if (depth<1) return Evaluate(); >>>>> MOVE move_to_search; >>>>> int best=-INFINITY; >>>>> GenMoves(); >>>>> while (GetNextMove(&move_to_search)) >>>>> { >>>>> PlayMove(move_to_search); >>>>> val = -MTD(depth - 1, -guess + 1); >>>>> UnPlayMove(move_to_search); >>>>> if (val>best) >>>>> { >>>>> best=val; >>>>> if (val>=guess) >>>> >>>>You missed a line here. Fail-hard is "return guess", fail-soft is "return val". >>>> >>>>Fail soft helps when you need to re-search, so it helps more in MTD (f) than >>>>PVS, and doesn't matter at all in pure alpha-beta. >>> ^^^^^^^ >>>I guess you meant a small typo here. doesn't ==> does >>> >> >>Actually I just forgot about hash effects at the next iteration. Without those, >>the statement would be true .. (as far as I can see) > >The hashtable is the thing that is refuting so so many algorithms... ...one of >them is for example no-progress pruning. With a hashtable it is an incorrect way >to search. I've "reverse engineered" the no progress pruning algorithm and it does not depend on the transposition table. Unless I've somehow reverse engineered it "improperly," the idea appears to be 100% sound to me. > >>Vas >> >>>> >>>>Vas >>>> >>>>> } >>>>> } >>>>> return (best); >>>>>} >>>>> >>>>>perhaps there is something very wrong with this? or perhaps it's used already, I >>>>>just noticed that on Aske Plaat's site he always uses an Alpha-Beta search with >>>>>0 width windowed searches, but doesn't this do the same thing? Is using >>>>>fail-soft type algorithms used in MTD(f) since it could well help zoom into the >>>>>correct score sooner? >>>>> >>>>>Cheers >>>>>Tor
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