Author: Robert Hyatt
Date: 16:57:59 02/03/02
Go up one level in this thread
On February 03, 2002 at 13:43:28, Jeremiah Penery wrote: >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? 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. > > >It seems this is what happened on the famous move 36 of game 2, where it >suddenly changed its mind from Qb6 to axb5. I don't know if it happened >elsewhere. Not at all, there. It just used way more time to find a new best move as the previous best move had dropped in score significantly.
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