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Subject: Re: Getting a PV using MTD(f)

Author: Tijs van Dam

Date: 09:21:18 02/08/00

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On February 08, 2000 at 11:01:00, Andrew Williams wrote:

>On February 08, 2000 at 08:54:22, Tijs van Dam wrote:
>
>>I have been reading about the MTD(f) algorithm that is also used by Andrew
>>Williams in PostModernist. I want to try it, but it has some things different
>>than a "traditional" search. I am wondering about the following: how do you get
>>a PV, or even a move to ponder?
>>
>>The best move is obvious: it is the last move that failed high at root. But when
>>searching that move, all moves in the child position must have failed low. So
>>which one of them is the best? Andrew, how do you do this?
>>
>>My first thought was doing an MTD search with shallow depth from the position
>>that follows the root move. Or maybe a PVS search?
>>
>>Who on CCC has experience using MTD?
>>
>>Greets,
>>Tijs van Dam
>
>I use my hash-table to keep track of the PV. If I've found a move at
>a position whose score is > beta, that move ALWAYS goes into the hash-
>table. I then rebuild the PV by stepping through these moves. It works,
>but often you find the end of the PV being truncated.
>
>BTW in PostModernist I hash moves in the qsearch as well.
>
>Andrew

Thanx, I'll try that. I've just converted my program to a first raw version, and
the results are so far so good. I think the hashtable storing needs some tuning.
Is hashing faster than researching the q-search for you?

Tijs



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