Author: Ulrich Tuerke
Date: 14:14:29 12/23/04
Go up one level in this thread
On December 22, 2004 at 17:33:44, Uri Blass wrote: >On December 22, 2004 at 16:50:40, Ulrich Tuerke wrote: > >>On December 22, 2004 at 16:27:13, Uri Blass wrote: >> >>>On December 22, 2004 at 16:19:05, Ulrich Tuerke wrote: >>> >>>>On December 21, 2004 at 05:11:13, Uri Blass wrote: >>>> >>>>>On December 21, 2004 at 03:53:49, Joachim Rang wrote: >>>>> >>>>>>On December 20, 2004 at 16:32:24, Jouni Uski wrote: >>>>>> >>>>>>>Shredder 8 reaches quite stunning averaga search dept. E.g. with only 15 >>>>>>>second/move average with Pentium 2400 and 128MB hash it averages 15,2 ply! For >>>>>>>comparison Fritz Bilbao and Gandalf 6 reach both same 12,7 ply. No wonder >>>>>>>Shredder beats them 13 - 7 and 14 - 6. Of course 2,5 ply is a lot difference! >>>>>>>Is there any amateur or pro engine, which can equal Shredder in depth - Junior's >>>>>>>half plys can be forgotten. >>>>>>> >>>>>>>Jouni >>>>>> >>>>>>Here is a 1-minute search on my Athlon XP@1540 MHz, with Shredder 7.04 default >>>>>>and Fruit X with aggressive delta, futility and history pruning. Both engines >>>>>>were analysing together under Arena. Compare the depth! >>>>> >>>>>I am surprised to read that fruit2 has history pruning. >>>>>I understood that Fabien does not plan to implement history based pruning and >>>>>here is the source of my misunderstanding: >>>>> >>>>> >>>>>The reason is the following link: >>>>>http://f11.parsimony.net/forum16635/messages/68164.htm >>>>> >>>>>Fabien claimed in that link: >>>>> >>>>>"Forward pruning in the main search is a separate topic that I don't intend to >>>>>address now. If I ever do, I expect it will require years of work (same for a >>>>>proper move ordering)." >>>>> >>>>>Note that I consider history based pruning as forward pruning in the main >>>>>search. >>>> >>>>Doesn't the history heuristic simply mean that moves which had often produced >>>>cuts in the previous iteration will be tried as killers ? >>> >>>No >>> >>>It means reducing depth of moves that almost always caused fail low based on >>>statistics. >> >>Hm ..., with the intention to avoid production of these nasty fail lows again by >>reducing their search depth ? > >No > >The intention is not to avoid production of these fail lows that I am almost >sure that I will get but to produce them faster. >Note that if I get unexpected fail high I research again to the original depth. >As far as I know this idea is used by Terra and Gothmog and smarthink. > >This idea was original idea of me and I thought not to share it but after sergei >markof (author of smarthink) already talked about it there is no reason to hide >it. > >I do not share the exact conditions that I decide to reduce depth but one of the >conditions is that based on history experience the move failed low in many cases >that it was tried and almost never failed high. > >history tables give you only the frequency of fail high so you need to build >different tables. I understand: thanks for the info and congrats for inventing a new idea ! Uli > >Uri
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