Author: Uri Blass
Date: 07:59:33 11/22/02
Go up one level in this thread
On November 22, 2002 at 10:52:03, Omid David Tabibi wrote: >On November 22, 2002 at 10:47:00, Uri Blass wrote: > >>On November 22, 2002 at 03:46:06, Tony Werten wrote: >> >>>On November 22, 2002 at 03:31:37, Uri Blass wrote: >>> >>>>On November 22, 2002 at 02:59:34, Tony Werten wrote: >>>> >>>>>On November 22, 2002 at 02:44:52, Tony Werten wrote: >>>>> >>>>>>On November 21, 2002 at 17:01:11, Omid David Tabibi wrote: >>>>>> >>>>>>>On November 21, 2002 at 16:55:04, Tony Werten wrote: >>>>>>> >>>>>>>>On November 21, 2002 at 16:19:17, Omid David Tabibi wrote: >>>>>>>> >>>>>>>>>On November 21, 2002 at 16:05:45, Tony Werten wrote: >>>>>>>>> >>>>>>>>>>On November 21, 2002 at 13:52:33, Omid David Tabibi wrote: >>>>>>>>>> >>>>>>>>>>>On November 21, 2002 at 13:05:28, Uri Blass wrote: >>>>>>>>>>> >>>>>>>>>>>>On November 21, 2002 at 09:16:09, Omid David Tabibi wrote: >>>>>>>>>>>> >>>>>>>>>>>>>On November 21, 2002 at 08:34:36, Uri Blass wrote: >>>>>>>>>>>>> >>>>>>>>>>>>>>1)I do not find in the pseudo code in figure 3 undo null move. >>>>>>>>>>>>>> >>>>>>>>>>>>>>I assume that it should be before if value>=beta and after value=-search(...) >>>>>>>>>>>>>>Am I right? >>>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>>That is why it is called *pseudo*-code :-) >>>>>>>>>>>>>You have to fill in the obvious parts by yourself... >>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>>>2)What is the value of the research for tactical strength? >>>>>>>>>>>>>>Should it help significantly relative to searching to reduced depth when >>>>>>>>>>>>>>value>=beta without research (even when we get value that is less than beta). >>>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>>I didn't understand the question. Dp you mean doing a shallow search even when >>>>>>>>>>>>>we don't have a fail-high report?! >>>>>>>>>>>> >>>>>>>>>>>>I meant to ask what is the tactical value of the research(You suggested people >>>>>>>>>>>>to start with doing it without the research first and only after it works to do >>>>>>>>>>>>it with the research) >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>>The re-search is needed only in zugzwang positions. Such zugzwang positions >>>>>>>>>>>occur very rarely in midgames; so you can forgo the zugzwang detection re-search >>>>>>>>>>>and still benefit all the improved tactical performance. >>>>>>>>>> >>>>>>>>>>I was quite surprised to see them from the starting position at a rate of 5 per >>>>>>>>>>second. Not impressive, XiniX searches 400 Kn/s there, but still surprising. >>>>>>>>>> >>>>>>>>> >>>>>>>>>The rate of what, was 5 per second? >>>>>>>> >>>>>>>>"Zugzwang positions" or rather, positions where nullmove would have given a >>>>>>>>cutoff but that after reducing depth and searching gave a score < beta. >>>>>>>> >>>>>>> >>>>>>>You mean you got an average of 5 zugzwang indications per second in middle >>>>>>>game?!!! Then your program has instabilities which cause a huge number of >>>>>>>needless re-searches due to false zugzwang alarm. Turn off your zugzwang >>>>>>>detection at once! >>>>>> >>>>>>I'm quite interested in finding out what is happening so I'll leave it in for a >>>>>>while. I think it has something to do with tempo. XiniX doesn't use futility >>>>>>pruning so I'm quite curious to know if programs that do, have a bigger false >>>>>>zugzwang count. >>>>> >>>>>Think I found it. Your algoritm doesn't seem to work correctly with threat >>>>>detection, causing instabilities. Maybe your testprogram didn't use it ? >>>> >>>>I do not understand >>>> >>>>Can you explain? >>>> >>>>I did not find something strange with the 5 "Zugzwang" per second in the opening >>>>position because I assume that it is all about the horizon effect and not about >>>>real zugzwang positions". >>> >>>Yes, and R=3 gets the horizon closer than R=2. Threats fe get found easier with >>>R=2. >>> >>>Tony >> >>I now checked with movei and counted 63 horizon effects in the first 10,000,000 >>nodes. >> > >By 63 horizon effects you mean zugzwang detection (they are two different >things!)? The algorithm does not detect zugzwangs but cases when null move search return beta and search to bigger depth returned a value that is smaller than beta. I do not believe in zugzwangs near the opening position so I guess that the reason must be some horizon effect. Uri
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