Author: Dieter Buerssner
Date: 14:26:21 03/24/04
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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. >>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. Regards, Dieter
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