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From: dwells@fits.cx.nrao.edu (Don Wells)
Subject: Re: scheduling software
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Message-ID: <DWELLS.91May31072617@fits.cx.nrao.edu>
In-Reply-To: jgb@prism.gatech.EDU's message of 31 May 91 02: 32:07 GMT
Date: Fri, 31 May 1991 12:26:17 GMT
References: <1991May30.135005.2616@macc.wisc.edu> <30248@hydra.gatech.EDU>
Organization: National Radio Astronomy Observatory, Charlottesville, VA
Lines: 26

In article <30248@hydra.gatech.EDU> jgb@prism.gatech.EDU (James G.
Baker) writes:
...
   Does your application approach an "NP-complete" problem?   You can quickly
   reach the "lifetime of universe" run-times if not careful.  Often, it
   is reduced to letting the computer to the "best it can" and then allow
   for some manual playing.  My scheduling gets it down to about a 6/200 
   ratio of problems.  The computer "could" do it, but would have to try
   all combinations potentially.  It also does it in about 45 seconds (a 
   nervous 45 seconds, that is :-).  Mine was on a PC for cost's sake.


Anyone who needs to solve scheduling problems which verge on
NP-complete should be aware of the SPIKE system which is used to
schedule the Hubble Space Telescope, a *very* difficult case. SPIKE
uses a neural net approach, with remarkable success. The key developer
is Mark Johnson at the Space Telescope Science Institute in Baltimore,
MD. A knowledgeable contact in Europe is Hans-Martin Adorf at the
Space Telescope European Coordinating Facility, located at the
European Southern Observatory in Garching bei Muenchen.
--

Donald C. Wells             Associate Scientist        dwells@nrao.edu
National Radio Astronomy Observatory                   +1-804-296-0277
Edgemont Road                                     Fax= +1-804-296-0278
Charlottesville, Virginia 22903-2475 USA            78:31.1W, 38:02.2N 
