Author: Tijs van Dam
Date: 14:32:31 02/08/00
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On February 08, 2000 at 12:40:02, Andrew Williams wrote: >On February 08, 2000 at 12:21:18, Tijs van Dam wrote: > >>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 > >Yes, it seems so. It's so easy to take it out and put it back in that I test >this quite often, and it's always been better with hashing in the qsearch. >Did you have a look at the web page I posted in the "Green List" thread? In >there it describes what you need to do to make your hash-table work with >MTD. > >Good luck and please keep us posted. > > >Andrew Yes, in fact that's what gave me the whole idea of using MTD. I'm experimenting a little, but I still use about three times as much nodes for calculating a position with fixed depth as I do with conventional alpha-beta. I will work on it this weekend and post the results. Tijs
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