Author: Uri Blass
Date: 09:47:23 10/03/03
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On October 03, 2003 at 12:13:13, Anthony Cozzie wrote: >On October 03, 2003 at 12:03:49, Uri Blass wrote: > >> >>I can detect every big threat by adding a special search after making null move. >> >>For example if I like to detect threats of at least 2.2 pawns I can do >>val=-alphabeta(depth-4,-beta+219,-beta+220,...) >> >>if (val<=beta-220) >>threatmove[ply-1]=1; >>//ply-1 because I still did not undo the null move. > >small error here: beta should be replaced by eval, or you will have massive >instability problems. If I am a queen down in the search and I threat to win a bishop then I do not consider it as a threat because a threat is a threat relative to beta. I believe that Tord does the same(he replied that your example of threating the queen twice by sacrificing material is solved by extending only big threats so if you sacrifice a rook and a bishop the threat on the queen is not a big threat). I think that the idea that an extension should not be dependent on beta is a bad idea. It is better to have stronger engine with stability problems and not weaker engine without them. I prefer even not to care about using hash tables for pruning because my experience told me that I cannot get significant gain there easily(I have a lot of stuff that means that pruning or extension is not defined only by the position). Uri
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