Author: Vincent Diepeveen
Date: 15:56:08 06/17/05
Go up one level in this thread
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. >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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