Author: Uri Blass
Date: 23:24:12 05/11/03
Go up one level in this thread
On May 12, 2003 at 02:03:05, Omid David Tabibi wrote: >On May 11, 2003 at 12:14:18, Uri Blass wrote: > >>On May 11, 2003 at 10:21:12, Omid David Tabibi wrote: >> >>>On May 11, 2003 at 07:19:04, Tim Foden wrote: >>> >>>>On May 10, 2003 at 21:23:00, Omid David Tabibi wrote: >>>> >>>>>On May 10, 2003 at 20:32:10, Matthias Gemuh wrote: >>>>> >>>>>>On May 10, 2003 at 17:49:01, Mike Siler wrote: >>>>>> >>>>>>>When Sjeng finishes a search, it displays among its stats a move ordering >>>>>>>percentage. Does anyone know how this is calculate? >>>>>>> >>>>>>>Michael >>>>>> >>>>>> >>>>>>In most programs, it is the ratio FailHigh_on_fist_move/All_FailHighs. >>>>>> >>>>> >>>>>Why not use a more general figure: >>>>>ratio of "first move being the best" / "all (interior) nodes" ? >>>> >>>>I think this is because there are generally 2 types of interior nodes... one's >>>>that do fail-high, and ones that don't fail-high. >>>> >>>>In the ones that fail-high, we are very interested on the fail-high happening on >>>>the first move. >>>> >>>>In the ones that don't fail-high, we generally fail-low (due to alpha+1=beta), >>>>we don't (in general) have a best move. And it will make hardly any difference >>>>what order we search the moves in, as we will have to look at them all anyway. >>>> >>> >>>That's true, but my point is that we shouldn't confine the figure only to >>>fail-high cases, but also consider other nodes which produce a best move. >>>Anyway, the total figure will not vary significantly. >> >>I do not understand how do you know if a move is the best during a normal >>search. >> >>Some facts: >>1)If the first move fail high it does not mean that it is the best move and the >>program only knows about a move that is good enough to refute the opponent move >>and does not search for the best move that does it. > >Well, it means that the move ordering was also "good enough" :) Not for me. There is a difference because I have pruning rules that are based also on evaluation and if I choose a better move first then I will probably need less nodes to refute the opponent move. I think that even for programs with only null move pruning starting with a better move will give less nodes in most of the cases. Uri
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