Author: Robert Hyatt
Date: 16:56:52 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? 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 They wouldn't "change". They would just be "longer". Because the chess hardware doesn't have any way to return what would be a variable-length PV back up the search tree. IE Imagine Crafty's output, but with the PVs simply chopped off short by a few plies plus all the q-search captures...
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.