[Coin-discuss] modeling with GNU MathProg

[Leonardo B Lopes]

Hi,

	Is the label object in the OSI CVS or elsewhere?

Thanks!
Leo.

Alan King wrote:
> 
> Hi Brady,
> 
> Thanks for sending this around.  It's great to have an opensource 
> version of AMPL.
> 
> Would appreciate any thoughts out there on structuring interfaces 
> between modeling methods and solver methods.  
> 
> For Stochastic Modeling Interface, we have to build labeling structures 
> and associate them with LPs.  As a starter, I have drafted a simple 
> version of a label object (implemented as a multimap) that can be 
> "attached" to the OSI to facilitate referencing rows and columns.  
> 
> At first glance, label information really belongs to the modeling method 
> side.  But specialized solver methods (eg decomposition, etc) need fast 
> ways to access substructures.  These can be identified through accessing 
> model information and then storing them in ways suited to the method.  
> 
> Maybe we should build a "model" class (OMI?) that has this function of 
> communicating between modeling languages and solvers.  
> 
> Alan
> 
> Alan King
> Mathematical Sciences, IBM Research
> http://www.research.ibm.com/
> http://www.research.ibm.com/people/k/kingaj/
> 
> University Relations: University of Washington
> http://www.washington.edu
> http://www.ibm.com/university
> 
> 
> 	*Brady Hunsaker <hunsaker at isye.gatech.edu>*
> Sent by: coin-discuss-admin at www-124.southbury.usf.ibm.com
> 
> 05/17/2003 08:21 PM
> Please respond to coin-discuss
> 
> 	       
>         To:        coin-discuss at www-124.southbury.usf.ibm.com
>         cc:        
>         Subject:        [Coin-discuss] modeling with GNU MathProg
> 
> 
> 
> 
> The most recent release of GLPK (4.0) includes a parser for the
> modeling language GNU MathProg.  It's not exactly a new language,
> since it's a subset of AMPL.  It contains all of the basic
> functionality of AMPL as far as I can tell, excluding things like
> loops, for example.  So now there is an open-source way to process
> many AMPL models.
> 
> Better yet, the parser provides its own API, although you have to look
> into the source code for documentation (the documentation there is
> reasonably good).
> 
> The attached tarball contains a function that uses this API to read a
> model instance into an OsiSolverInterface object.  It needs to link
> against the GLPK 4.0 library as well as whatever OSI libraries are
> being used.  I included an example which reads in a model and solves
> it using CLP.
> 
> I thought this was important enough to get such a function out there
> quickly.  However, I'm writing my dissertation right now, so I won't
> have time to do much more in the near future.
> 
> I'm hoping that someone else will be interested enough to take on the
> task of better integrating this into OSI.  As I see it there are two
> main issues:
> 
> 1. Currently OSI does not provide an easy way to identify rows or
> columns other than by index.  This is an issue since it's not
> obvious which model constraints or variables will get which
> number.  My current implementation isn't really that useful because
> of this.
> 
> 2. What is the best way to include the parser?  That is, where can we
> include this or a similar function in COIN-OR?  Right now I'm
> linking against the GLPK library, which requires that the user
> install GLPK.  It would be possible to create a stand-alone parser
> for COIN-OR by extracting the necessary parts of GLPK, but this
> would have to be licensed under the GPL (I don't think that's a bad
> thing, but we probably can't do it until we're incorporated, if
> then).  Maybe there are other possibilities.
> 
> I'm happy to talk about this, though I can't justify much more coding
> right now.
> 
> Brady
> 
> ----------------
> Brady Hunsaker
> Georgia Institute of Technology
> Program in Algorithms, Combinatorics, and Optimization
> School of Industrial and Systems Engineering
> 
> E-mail address:   hunsaker at isye.gatech.edu
> 
> 
> 
> #### ReadGNUMathProg.tar.gz has been removed from this note on May 19, 
> 2003 by Alan King

-- 
=======================================================================
Leonardo B. Lopes                                      leo at iems.nwu.edu
Ph.D. Candidate                                           (847)491-8470
IEMS - Northwestern University             http://www.iems.nwu.edu/~leo