Author: Tord Romstad
Date: 14:33:23 03/24/04
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On March 24, 2004 at 17:26:21, Dieter Buerssner wrote: >On March 24, 2004 at 17:14:26, Tord Romstad wrote: > >>On March 24, 2004 at 16:52:04, Dieter Buerssner wrote: >> > >>>Are there cases, where ETC on needs one depth more, to solve a tactical >>>problem, than ETC off? I would guess, that this could be the case now and >>>then. >> >>I am 100% sure it happens now and then, and I'm also 100% sure that the >>opposite thing happens. > >Yes, I don't doubt, that the opposite can happen (although it would not happen >in a plain alpha-beta search without extensions/pruning). > >>One of the things I consider when making pruning >>and reduction decisions is the history of the move. Moves which have >>very rarely failed high in the past are more likely to be pruned or reduced. >>Of course, it will happen many places in the tree that one particular move >>at one particular node is pruned with ETC disabled and not pruned with >>ETC enabled, because the history count of the move will be different in the >>two cases. >> >>Even tiny changes in my move ordering often results in a tactical problem >>being solved one ply earlier or later. > >No doubt about this. Without having it tried yet, I feel that ignoring extension >decisions for ETC is more severe, however (somehow like a first order error >term, while other things you mention are second order error terms). After all, >we think we have a good reason to extend some moves. Getting a cutoff into the >search tree (or better graph) by ignoring that reason seems dubios to me. It is very possible that you are right, and I should certainly do some experiments with this again. Thanks for reminding me. >>>Are you trying ETC after hash probing and before null move? >> >>No, after both. > >Can you elaborate? I don't see the sense in doing this twice. Sorry, I wasn't clear enough. I don't do it twice. I do hash probing first, then null move, and finally ETC. Tord
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