Author: Robert Hyatt
Date: 18:20:56 01/10/01
Go up one level in this thread
On January 10, 2001 at 16:00:59, David Rasmussen wrote: >On January 10, 2001 at 12:21:17, Robert Hyatt wrote: > >>On January 10, 2001 at 10:13:44, David Rasmussen wrote: >> >>>On January 09, 2001 at 15:56:16, Robert Hyatt wrote: >>> >>>>On January 09, 2001 at 13:59:59, Larry Griffiths wrote: >>>> >>>>>[D]R7/P4k2/8/8/8/8/r7/6K1 w - - >>>>> >>>>>Hopefully this position will show up visually. >>>>> >>>>>I have been testing my minmax again and using Crafty's perft command to verify >>>>>the possible moves at each ply. I entered this WAC018 position using setboard >>>>>in crafty. Crafty and I match until ply 5. >>>>> >>>>>Crafty gets... >>>>> >>>>>White(1): perft 1 >>>>>total moves=9 time=0.00 >>>>>White(1): perft 2 >>>>>total moves=147 time=0.00 >>>>>White(1): perft 3 >>>>>total moves=2335 time=0.00 >>>>>White(1): perft 4 >>>>>total moves=39892 time=0.03 >>>>>White(1): perft 5 >>>>>total moves=731140 time=0.58 >>>>>White(1): >>> >>>Exactly what does perft do? How can I implement it in my own program? >> >> >>It takes whatever position you set up on the board, then does a _full_ >>search to the depth you give. IE if you try it from the starting position, >>to depth=1, you will get a count of 20 moves. It simply tells you _exactly_ >>how many positions are in such a tree, using no search extensions, no q-search, >>or anything. It is more of a sanity check on your move generator than it is >>anything else. But it will catch a stray bug here and there... > >You mean a full minimax search, no alpha/beta either? Yes.. except no minimaxing is done, as no score is computed. it just generates all the ply=1 moves, makes the first, generates all the ply=2 moves, etc... the idea is to see how many 'nodes' are searched to a fixed depth with no extensions or pruning of any kind. Everybody should match _exactly_ as this only counts legal positions...
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