Author: Uri Blass
Date: 09:01:54 11/22/02
Go up one level in this thread
On November 22, 2002 at 11:40:35, Tony Werten wrote: >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. > >I looked at some of the positions and they weren't zugzwang positions. So my >best guess is also horizon. Probably combined with "tempo" wich is quite >important in the beginning. > >Tony It seems that I had a bug of initialized local varaible First positions was no zugzwang 36 positions out of 10,000,000 if I have no bugs now. Uri > >> >>Uri
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.