Author: Carmelo Calzerano
Date: 15:46:00 08/24/01
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On August 24, 2001 at 15:45:28, Tony Werten wrote: >On August 24, 2001 at 15:18:04, Carmelo Calzerano wrote: > >>On August 24, 2001 at 13:47:12, Tony Werten wrote: >> >>>On August 24, 2001 at 09:19:23, Robert Hyatt wrote: >>> >>>>On August 24, 2001 at 04:31:27, Tony Werten wrote: >>>> >>>>>Hi all. >>>>> >>>>>I like to know if there are some solutions for this problem. >>>>> >>>>>My program searches for 4 minutes, gets to 14 ply (or whatever), makes a move, >>>>>takes a pondermove and starts pondering. >>>>> >>>>>Now the first 12 ply are taken from the hashtable (<1 sec ) but it starts an >>>>>(almost) uninformed 13 ply search from which it is never going to return in the >>>>>allocated time, so it's just taking the best move it had from the previous >>>>>search, which is costing me plydepth. (and games ) >>>>> >>>>>Any ideas, sugestions ? >>>>> >>>>>cheers, >>>>> >>>>>Tony >>>> >>>> >>>> >>>>Internal iterative deepening can help here. The problem is that if your >>>>first move comes from the hash table with a good score (typical on pondering) >>>>then you reach depth N with a PV that has only that move in it. (there are >>>>things you can try to do, such as extending the PV in such cases by probing >>>>for the second position, etc when you back up the PV). IID works by doing >>>>shallow searches to find good moves at PV-type positions where you have no PV >>>>move. If you don't do something like this, you reach critical positions with >>>>no real hope of having the best move searched first, which makes the tree >>>>explode in a bad way... >>> >>>I use IID but that isn't the problem. I get the PV from hashtable and do get a >>>full length PV. So at ply 1 I get a 12 ply PV, as on ply 2,3 etc. All within a >>>second. Then I reach ply 13 and get into problems. >> >>Here I don't understand: don't you get a 12 ply PV (better, a PV which comes >>from a 12 ply search) when searching at depth 1, 2, ... 12? If so, you should >>have the same PV when searching at depth = 13, which is all what you need... >>What am I missing here? > >Having only a 12ply pv in a 13 ply search isn't really going to help you if you >want to finish the search in a reasonable time. Why not? When you start an N ply search, usually you have just a N-1 ply PV to guide you. That's what iterative deepening is all about, AFAIK :-) Bye, Carmelo
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