Author: Ed Schröder
Date: 02:47:21 02/01/02
Go up one level in this thread
On February 01, 2002 at 00:24:07, Robert Hyatt wrote: >On January 31, 2002 at 15:19:38, Ed Schröder wrote: > >> >> >>Okay 9 plies it is, it does not matter. >> >>Here is a snip from the "IEEE MICRO" journal from 1999. It says 4 plies in the >>hardware AS PART of the iteration, thus not ADD TO the iteration. The text is >>below. >> >>Reading the June 2001 article I seriously doubt DB has shared memory for its >>hash table although it's not entirely clear to me. If true that is about the >>biggest search killer there you can imagine which makes a 16-18 ply (brute >>force) search claim even more ridiculous. Text below. > > >DB definitely did _not_ have shared memory. The SP2 has no shared memory, it >is a very fast message-passing system. Here you go.... Brute force, massive extensions, no shared memory. 16-18 plies is impossible. >The 4 plies makes no sense to me in any context, as Deep Thought searched >4-5 plies in hardware, while deep blue searched 5-7 according to Hsu. This >depth is pretty-well fixed by the speed of the SP2. The deeper the hardware >goes, the slower a search goes and the host software ends up waiting on the >chess hardware. If the chess hardware searches too shallowly, say 4 plies, >then the host software can't keep up. For a given position/depth, there is >a very precise "hardware depth" that optimizes performance... > >All explained by Hsu several times of course... You snipped Hsu's own text that explains the opposite. It says 4 plies in the hardware AS PART of the iteration, thus not ADD TO the iteration. Again... ======================================================= The search occurs in parallel on two levels, one distributed over the IBM RS/6000 SP switching network and the other over the Micro Channel bus inside a workstation node. For, say, a 12-ply search, one of the workstation nodes—working as the master for the entire system—would search the first four plies in software. (A ply represents a move by either player.) After four plies from the current game position, the number of positions increases about a thousand times. All 30 workstation nodes, including the master node, then search these new positions in software for four more plies. The number of positions increases by another thousand times. At this point, the chess chips jump in and finish the last four plies of the search, including quiescence search. Partitioning the search into the (two-level) software search and the hardware search per-mitted a great deal of design flexibility, yet maintained overall search speed. The software handled less than one percent of the total posi-tions searched, but it controlled about two thirds of the search depth. The software por-tion of the search can be arbitrarily selective without slowing down the system. The eight plies of software search performed on the RS/6000 SP included many compli-cated search extensions, which extended the search deeper along lines the computer con-sidered “forcing.” Some experimental evidence suggested that the playing strength would increase significantly if the search extensions went all the way down to quiescence search. Implementing the full software search exten-sions on the chess chip seemed too risky a proposition, given the design time constraint. During the 1997 match, the software search extended the search to about 40 plies along the forcing lines, even though the nonextended search reached only about 12 plies. DEEP BLUE IEEE MICRO ================================================= >>>Did you see the email from the DB team? Is there any misunderstanding that? >> >>Please post. >> >>Ed >> > >I did, twice, in response to Vincent... Sorry no email of DB team seen in this thread. Perhaps you mean your own interpretation of something nobody ever saw? Scrolling back I find this one: http://site2936.dellhost.com/forums/1/message.shtml?210978 It says 11 plies against Kasparov. It fits. Your 12(6) = 18 is a fairy tale. Ed
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