Author: Uri Blass
Date: 02:29:07 02/03/02
Go up one level in this thread
On February 03, 2002 at 04:04:45, Graham Laight wrote: >On February 02, 2002 at 12:01:53, Robert Hyatt wrote: > >>As I mentioned in the past, on more than one occasion they had said "we did >>an N ply search there" and when I saw their output it said N(X). I didn't give >>it any thought until I finally asked "what is that X value?". And Murray or >>Hsu explained it. I then asked "why did you say N ply?" and one of them >>responded "the hardware search is much simpler than the real software search >>and we tend to think of that as a unique form of a 'static evaluation' even >>though it does include a search + capture search." >> >>IE I guess that if I had had that kind of design, I would probably shorten >>the reference to depth to just include the software depth since (at least for >>deep thought) it seemed that the hardware depth was generally statically fixed >>to 4 or 5 (I don't recall exactly which I saw). DB seemed to be a bit more >>dynamic in that they could do an 9(5) iteration and then either a 10(5) or >>9(6) iteration next. >> >>That was why I specifically asked the question about the depth, because I had >>seem them use "depth" in what I considered to be an ambiguous way and after we >>all started examining their logs it seemed important to understand their stuff. >> >>There are other "hints" about this. Remember that the chess hardware has >>absolutely no way to return a PV move of any kind. So _every_ PV you see >>produced by their program was absolutely searched by the software part of >>the machine _only_. When you see 10(6) you can now _know_ that in addition >>to whatever PV you see (and it may well not be a full PV as they could only >>get the PV from the hash table which is not 100% reliable in producing moves >>particularly near the end of a PV) there _must_ be at _least_ 6 more PV moves >>(non-captures) plus the q-search moves. The Chess processors didn't do SE, >>but it did do classic extensions like in-check and recapture, because it was >>copied directly from Belle which did the same things. >> >>In short, _every_ PV you see has at least (N) more non-capture moves on the >>end of it, plus their q-search... If you look at their output carefully, >>you begin to get the idea of their search, because it is _definitely_ a fact >>that the hardware provides no PV information of any kind, period. Look at the >>PVs you see and when you realize that they can only come from the X(Y) (the X >>part only) part of the search, things begin to make sense. Vincent sees a >>8(4) depth and 12 moves and says "aha, that is obviously a 12 ply search and >>PV" even though it should now be obvious that that 12 ply PV came from the 8 >>part of the software search, not from the 4 part of the hardware search. > >If the chess chips did not produce a PV (Position Valuation), then what was >their output, and how did it contribute to the move selection, please? pv means principal variation and not position valuation. Uri
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