Author: Tony Werten
Date: 00:01:32 08/26/04
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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? It can and will happen quite often. The basic problem is when you have an advantage, wich I will take away from you in a couple of moves. ie suppose you have rook on the 7th, wich will be attcked by my knight in two moves, if you don't move it away I will capture it on the 3rd move. If a nullmove search reduces depth enough to not let me make this 3rd move, you will still get the RookOn7th bonus, wich it would get if you would normaly search and do reach my 3rd move. That's why nullmove hurts positionally (an tacticly). As a compensation, it will let you search deeper and improve both tactics and positional. If all is well, the improvement should be higher than the loss. Tony > >Thanks, greetings Bert
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