Author: Jeremiah Penery
Date: 16:13:34 10/13/02
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On October 13, 2002 at 17:19:50, Vincent Diepeveen wrote: >On October 13, 2002 at 16:55:32, Jeremiah Penery wrote: > >first of all. in endgames when i search dual i get huge mainlines. >sometimes 25 ply and i have a nominal search depth of like 15 then. > >if i add a bunch of processors i sometimes get weird long mainlines >because it searches nonsense. > >this is a well known phenomena. If you're getting a _big line_ of nonsense at the end of your PV, then you're probably trying to get the full PV from the hashtable or something. I have never seen such a thing with Crafty. (Of course, the last move or two can be nonsense, but more often that's because of very low remaining depth, causing easy tactics to be missed.) I haven't examined Deep Blue's mainlines to see if they contain a lot of junk or not, but I have seen at least a few times where some nonsense appears near the ends. They probably were trying to reconstruct the software PV from the hashtable also, and hardware couldn't return any PV of course. >now they search very small search depths with a big number of processors. > >So they all search incredible nonsense. > >also we know they extended a lot for not so common reasons. > >that explains obviously a lot. > >so the only reliable mainlines is the first mainlines of a game. we just >have 6 games as you know. Do you mean the mainlines of searches after they were out of book, or while they were in book? >after that the hashtable is filled with nonsense of a few ply which adds >up quickly. extensions do the rest of the job. Then do you want me to make the table (of depths x(y) with the corresponding length of mainline) with just, say, the first 10 moves of each game? I can already tell you the results are not much different than the results for the full game.
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