Author: Bas Hamstra
Date: 13:23:03 09/25/99
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Hello Bob, I just wanted you to know it works ok. Very flexible. I am still having a problem with the mate (nullmove returns mate) extension, though. That thing never has worked very good for me. Do you use it? Currently I am trying this settings, after some fiddling: (1 ply = 100) - OneReplyMate = 120 - Check = 60 - Recapture = 30 - NullReturnsMate = 80 I don't extend when Depth > 2*RootDepth, except for OneReplyMate, which doesn't seem to cause problems. I somehow feel more could be done with the NullReturnsMate. Now it solves a few wac's extra for me, with sometimes quite some overhead. It seems to be able to spot forced lines, but I don't think my program profits enough from them. Are there any tricks? Regards, Bas Hamstra. On September 24, 1999 at 10:15:27, Robert Hyatt wrote: >On September 24, 1999 at 08:14:05, Bas Hamstra wrote: > >>What are good ways to control extensions? I like the idea of extending part of a >>ply, but am not sure how to implement it. >> >>Suppose you have a depth 5 to search. Then if you wanted to extend 1/2 ply then >>there are now 2 available extensions. You extend here. Next ply: depth=4. How >>many available extensions? At first I thought 4/2 = 2, but already used 1, so 1 >>left. But I think this is not quite correct to subtract "history" extensions >>from the available extensions this ply. But how else??? >> >> >> >>Regards, >> >>Bas Hamstra. > > >First, for simplicity, lets count plies by 100. So a five ply search starts >with a depth of 500. For every ply you advance into the tree, you decrement >this by 100. So it works as always and the *100 doesn't do a thing, yet. But >now we extend by 3/4 ply, say (for some reason at the root of the tree) so our >depth is now 575. This does nothing (yet) as when depth drops to < 100, we >treat it as zero. So we are still doing a 5 ply search. But _if_ we extend >by a fraction of a ply at another point in the tree, 575 + 75 = 650 and _now_ we >are really doing a 6 ply search, not 5. But notice how it took two extensions >at two different plies, to make this happen? Which lets you sort of say "if >something interesting happens at two different nodes in the same path, then I >will extend that deeper than if something interesting only happens one time in >a path..."
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