Author: Ralf Elvsén
Date: 17:57:26 02/03/02
Go up one level in this thread
On February 03, 2002 at 07:40:27, Albert Silver wrote: >>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. > >I'm a bit fuzzy on the accuracy of the PV we're seeing in the logs then. >Presuming that the PVs are only the software PVs, then these may still have been >subject to changes afterwards, no? After all, it's not uncommon to search to a >given depth and say that move A is best, but with greater depth (as the hardware >will provide) move B is shown to be best. I haven't examined the logs in detail >as some here have, so I'm presuming that such an inconsistency isn't there, but >if the hardware extensions aren't capable of changing the decision making, what >good are they? I interpret your question as that it is not impossible that you have misunderstood something: you may think (or may not...) that the PVs shown are based solely on a software search. This is not so, The hardware search is always there (as far as I understand) and is doing the late part of the search. They can not just back up the PV. The effect is just as if some ordinary program searched to ply 12 but decided (for some reason) not to show any PVs longer than 8 plies. The last plies still influences the search. Pardon if you didn't think so. Ralf Or were they simply fortunate that this never happened in the >match and that is why we don't see it in the logs. I.e. a main move in the >software-based PV that was different from the move actually played due to later >corrections provided by the hardware extensions. > > Albert
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