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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