Author: Bas Hamstra
Date: 17:45:48 07/25/02
Go up one level in this thread
On July 25, 2002 at 16:58:58, Robert Hyatt wrote: >On July 25, 2002 at 14:06:39, Bas Hamstra wrote: > >>>>>IID is not a huge thing. It mainly helps where you fail high but can't get >>>>>a real score so that the next iteration, you end up with no hash moves for >>>>>the PV search... IID will supply good moves. >>>> >>>>All you get is a reasonable move from a D-2 search. Why not store the original >>>>hashmove in stead? >>> >>>Where would you get it from? I use the fact that there is no hash move >>>for a PV node to trigger the IID search... >> >>>>So when you normally store a UPPER score, in stead of saving >>>>no move at all, you save the original hashmove? I don't see why IID would >>>>provide a better move than that... >>> >>>Because at the _next_ ply in the tree, you have no move because it is a >>>fail low position... >> >>I don't understand. In case of a fail-low position I store the *original* >>hashmove which was a bestmove. So, I never am without hashmove. > > >You _must_ be without one at times. How can you store the "original" >best move is there is no hash entry there at all? > >I'll bet that if you count the number of times you call hash probe, and >the number of times you don't get a "hit", the difference will be extremely >high. And in _each_ of those misses, you don't get any kind of hash move >at all. Which is where IID helps. I have done that. As far as I know it only happens in the last 1-2 plies. Maybe it will worsen somewhat if the hashtable is full. Bas.
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