Author: Robert Hyatt
Date: 10:52:12 09/19/99
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On September 19, 1999 at 12:11:39, Bas Hamstra wrote: >Hello friends, > >When you do nullmove everywhere, it causes a lot of qsearches. Without nullmove >I have a good qnode/node rate, roughly around 5-10% or so. With nullmove that >worsens quite a bit, I see rates over 100% frequently. Is that normal? > >I read about nullhashing, a few times. I don't hash the result of a nullmove >search. To be more precise: when a position is cut by a nullmovesearch I don't >put that position in the hashtable, and just return Beta. Should I? And has that >got something to do with the bad qrates I'm seeing? can't answer that, but I don't see why you don't hash the result, as it is obviously the right answer in that position... I always do a hash store before I fail high, except when the fail high is after a hash probe, of course.. > >Can someone give a few pointers for nullhashing? Just putting a position that is >about to be cut by nullmove in the table, as a normal upperbound record, but >without a move? With flag "NULLHASH"? Record only to be used by nullmove, so >store with adjusted depth = depth-R ? That's how I would figure it, and I tried >it quickly, but without much result... > I store no move, a LOWER flag, and the normal depth.. >A second question: I don't store leaf-nodes at all, just see no point in that. I >would like to check if that's normal. A simple yes is enough :) > I don't. I used to. The only reason I don't is that it reduces hash table contention and lets me get away with smaller tables when memory is not as big as I'd like... >Regards, >Bas Hamstra.
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