Author: Robert Hyatt
Date: 07:44:18 05/31/01
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On May 31, 2001 at 08:56:33, Gian-Carlo Pascutto wrote: >On May 30, 2001 at 15:14:46, Robert Hyatt wrote: > >>3. When I fail high, I just relax >>beta to +infinity, rather than the tiered approach I used in Cray Blitz. If >>there are lots of mates here, that are not forced, the program still has to >>search them all out as with +infinity, you get zero beta cutoffs at positions >>where white is to move, until you establish a better beta value after a lot >>of searching. > >Silly question...why don't you do it in Crafty? It's not like it's >hard to code, and it gives real benefits. > >I use the CB approach after you once described it here or on rgcc and >it's saved my ass a dozen times... > >-- >GCP That is actually a good question. I guess I have simply not stopped to think about it, but it was obviously a reasonable idea. Harry had this one ugly position that at depth=12 would fail high, but we could not get a score back from ever. We discovered that the problem was that if we relaxed beta to +inf, about 90% of the positions were mates. Very deep mates. But not forced. When we put in the tiered fail-high, the problem went away. It has been on my to-do list for years, but I simply haven't gotten to it...
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