Author: Uri Blass
Date: 01:30:15 11/28/02
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On November 28, 2002 at 03:49:28, Sune Fischer wrote: >On November 28, 2002 at 03:43:14, scott farrell wrote: > >>On November 27, 2002 at 14:02:29, Stan Arts wrote: >> >>>Hello! >>> >>>I am wondering how strong you can go by not using pruning methods like null-move >>>or futilitypruning etc. but basicly just use a minimax-type algorithm with >>>some form of alpha-beta pruning. I mean to keep the "full-width" (depth before >>>going into Q-search) depth 100% sound. >>> >>>How well would the strong programs of today do when they dis-able (in theory, >>>might not be possible ofcourse) all types of pruning except alpha-beta? (keeping >>>their Q-search and move-ordening as it is now) >>> >>>Would be interesting to find out, I mean to see the effect of very good move- >>>ordening of advanced programs etc. Also it would probably show which programs >>>depend most heavelly on their Q-search that probably makes a lot of difference >>>in strength in this case too? >>> >>>PS. Are there any strong engines/programs that do NOT use null-move, or a whole >>>lot of futility-pruning/razoring etc? And if so, which ones? >>> >>>Thanks! >>> >>>Stan >> >>Read my recent post titled "pruning vs extensions vs qsearch - are these all >>effectively the same?" >> >>My argument is that you dont need to forward prune at all, if you extend enough, >>it is virtually the same thing. >> >>Are you aware that deep blue did NOT forward prune OR null move ??? just lots >>and lots of brute force and extensions. > >I don't think it is the same entirely. >One difference is that with pruning you can "undo" the extension you did >earlier. Ie. in a long variant you may extend at ply 2, but at ply 3 there are >some moves with should be pruned rather than extended. > >I see no way of doing this only with (positive) extensions. > >-S. You can do it by not extending at ply 2 but remembering a flag and extend at ply 3 only if the rules of the original program tell you not to prune at ply 3. I think that the pilosopical point that you can avoid pruning and do only extensions is not important. I do not need to look for some strange ways to define extensions only to avoid prunings. Uri
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