Author: Robert Hyatt
Date: 15:19:25 07/02/04
Go up one level in this thread
On July 02, 2004 at 04:14:50, Steve Maughan wrote: >Bob, > >Thanks for the reply, > >>If you are talking about PVS, where you search on a null-window and fail high, >>then re-search on a normal window and fail low, the fix is easy. If you fail >>low, _ignore_ the fail high, keep the old best move, and keep searching. > >Yes this is what I currently do. The situation that I'm concerned about is when >I have a tactical position where, for sake of argument, the key move is Bxg6+. >Monarch fails high on Bxg6+ at ply 7 only to fail low on the research. The same >is repeated at plys 8 and 9 until it find the solution at ply 10. Clearly >Monarch is "seeing" something at ply 7 but is not able to resolve it until ply >10 - this seems a bit odd - probably a bug of some sorts. > >Having make the original post I'm thinking that the bug will most likely reside >in the hashing code. That's the first place I'll look. > >Thanks again, > >Steve This is _not_ unusual. you store bounds and scores. Bounds can cause fail highs, but then will not help produce a true score so you can fail low. It is an artifact of inexact draft match hashing. IE using an entry from a deeper search to make a shallower search more accurate...
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