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Subject: Re: MTD(F) results

Author: Tord Romstad

Date: 04:05:42 12/18/03

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On December 17, 2003 at 16:52:50, Dann Corbit wrote:

>On December 17, 2003 at 16:37:15, Dann Corbit wrote:
>>On December 17, 2003 at 05:38:52, Tord Romstad wrote:
>>>On December 16, 2003 at 21:22:56, Anthony Cozzie wrote:
>>>>Recently I experimented with adding MTD(F) into Zappa.  It has been an
>>>>interesting experiment, but I am going back to PVS().
>>>>I thought that since Zappa has a [UL,LL] paired transposition table and an
>>>>evaluation granularity of only 1/100 of a pawn,
>>>I use 1/64 of a pawn in Gothmog.  In the new engine I am writing, the
>>>granularity will be configurable by the user, with possible values between
>>>1/8 and 1/512 of a pawn.
>>Here's an idea:
>>Start searching with a granularity of (a-b)/k,
>>and for every iteration change the granularity to the new value.
>>The values a and b are the start and end of the search interval being searched
>>and k is some integer constant used to tune the program (e.g. 8).

Thanks, it's certainly an interesting idea, and I will see if I can make
it work.  I'm afraid it will cause some non-trivial transposition table
problems, but perhaps they will be possible to solve.

>The idea works even better with MTD(bi) [A.K.A. the C* algorithm]

Like most others, I actually use a sort of hybrid MTD(f)/MTD(bi) search.


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