Author: Uri Blass
Date: 08:20:45 09/04/03
Go up one level in this thread
On September 04, 2003 at 11:00:41, Robert Hyatt wrote: >On September 04, 2003 at 09:56:21, Anthony Cozzie wrote: > >>On September 03, 2003 at 13:59:40, Robert Hyatt wrote: >> >>>On September 03, 2003 at 13:51:34, Gian-Carlo Pascutto wrote: >>> >>>>On September 03, 2003 at 13:48:21, Robert Hyatt wrote: >>>> >>>>>Mine is tunable. I run about 100 positions and pick the minply value that >>>>>optimizes all 100 the best. I just checked and I am using 3 at the moment. I >>>>>have not tested this recently. I think 3 was the optimal value for my quad >700. >>>>> >>>>>I will probably test this again on my dual to be sure that I have already done >>>>>this correctly. >>>> >>>>You ignored my point, which is that saying that if you'll just split at 4 ply >>>>to alleviate that problem causes another problem. >>>> >>>>It's not 'free' >>>> >>>>-- >>>>GCP >>> >>>I never said _anything_ is "free". However "optimal" != "free" in this >>>case. And since I have no choice, I go for optimal, whatever that is. There >>>is a cost for splitting. If that cost is high, you have to limit the number of >>>splits. Also, for obvious reasons, move ordering near the root is _far_ better >>>than move ordering near the tips. Splitting where ordering is better is >>>always a good idea. >>> >>>Note that I don't "just split at 4 ply" I split when there are >= N plies >>>remaining in the search, where N can be set. I use 3 for the moment. I have >>>run with 4 and 2 as well in the past, but for my program, my hardware, 3 was >>>best last time I tested. >>> >>>I have noted that hardware influences this. On my P6/200 quad box, N=2 was >>>better. >> >>also note that Diep & Sjeng probably have better move ordering than crafty > >Based on what? My fail high percentage on the first move is as high as >anybody's I have seen. That is the critical measure. How many times, when >you fail high, does it happen on the first branch as opposed to the second or >later? The higher the percentage, the better. I think that this may be misleading comparison because it is also important if the second move fail high or the third move fail high. I can understand why slow searchers can have better move ordering. They can let themselves to calculate information for better move ordering when for you calculating the same information may be too expensive and the gain may be smaller than the time that you spend for the calculations. I express no opinion about comparison between Crafty and other programs but only explain a reason to believe that Crafty can get worse move ordering relative to slower searchers. Uri
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