Author: Dann Corbit
Date: 17:36:38 08/25/04
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On August 25, 2004 at 17:37:59, Bert van den Bosch wrote: >First of all, I hope the forum will continue in some way! > >Before it is gone, I have a question. > >I wanted to check my null move so I tested if the null move would create a >cutoff, and after that I did the normal stuff. So if you have a cutoff with null >moving you are almost sure you will also get a cutoff with the normal proces, >except for zugzwangs of course. But this wasn't happening all the time when I >tested it, and usually the values involved from what I got back from nullmove >and from the normal process were just a few centipawns in difference. Could this >be because of search instabillity? If it isn't a bug in my program I had the >idea to search nullmove with beta-MARGIN in order for the value returned by null >move to bridge the few centipawns gap. And taking MARGIN the few centipawns. But >I'm not sure if that is correct. Can someone shine a light on this? If the board is crowded, you should almost always get a cutoff. If the board is nearly bare, then zugzwang positions become more common. Omid David Tabibi and Nathan S. Netanyahu wrote a paper on "Verified Null Move" that takes the assumption that checking the null move is a good idea. Since (after all) it is worse than doing nothing, a quick search should verify it. See this stuff: http://www.cs.biu.ac.il/~davoudo/pubs.html
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