Author: Frank Schneider
Date: 23:42:18 05/05/99
Go up one level in this thread
Hi James! On May 05, 1999 at 12:35:50, James Robertson wrote: >On May 05, 1999 at 02:18:11, Frank Schneider wrote: > >>On May 04, 1999 at 20:51:00, James Robertson wrote: >> >>>Whenever my program makes an extension, say, at depth = 4 it finds it is in >>>check, it will not do any futility pruning/razoring for the rest of the branch. >>>I recently read that some programs will do pruning/razoring even if there is an >>>extension, unless it is at the current ply. >>Gromit is one of those programs. It uses part-ply-extensions and has lots of >>them, therefore there are extensions in many paths of the tree and switching >>off futilitypruning after an extension would result in a much larger tree. >> >>>Is this a better way to do things? >>>It seems like it would nullify some of the effects of extending, but it could >>>also save a tremendous amount of time too. What should I do? >>Test what works better for you. >>(I've never tried switching off pruning if an extension applied - I'll try >>that sometime). >> >>> >>>Thanks for any help, >>>James > >I tried out both ways on the first 50 positions in WAC, and the version that did >not switch off pruning was about 20% faster. I made a mistake and ran the new >version at 5 seconds a move, while the old one at 10 seconds, and the new still >solved exactly as many as the old! So it seems it is better not to switch off pruning (I'll test switching it off later). One remark: using the first 50 WAC positions as a testsuite it is no surprise that both versions solved the same positions. Doing 7-ply-searches Gromit quickly solves WAC1 and WAC3-WAC50 but to find WAC2 Gromit really needs some time. IMO there are only 20-40 interesting positions in WAC, therefore I'd suggest using for example ECM which has more positions (>700) and more difficult positions (Gromit solves about 520/770 doing 8-ply-searches). So far I have only little experience with ECM (I used WAC before, too), but it seems to be a good choice. The drawback is that it takes a long time to test so many positions, therefore it has to done automatically (for example at night). Frank
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.