Author: Robert Hyatt
Date: 22:30:30 09/25/99
Go up one level in this thread
On September 25, 1999 at 16:23:03, Bas Hamstra wrote: >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? Yes... I have used it since Bruce first mentioned it. > >Currently I am trying this settings, after some fiddling: > >(1 ply = 100) > >- OneReplyMate = 120 >- Check = 60 >- Recapture = 30 >- NullReturnsMate = 80 > I use ply=60. using that, check = 60, one legal reply to check = 45, recapture extension=45, push passed pawns=45, threat (null move mate)=45. IE basically (at present version, anyway) everything is 3/4 of a ply except the basic check extension... >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? if you use failsoft, you can extend even if null move returns mated in N, rather than just mated... > >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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