Author: Uri Blass
Date: 08:55:07 11/22/02
Go up one level in this thread
On November 22, 2002 at 10:59:33, Uri Blass wrote: >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 Another possible explanation is a bug in counting and checking the first position suggest that I really had a bug. It seems that I have less horizon effects. Uri
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