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[Help-glpk] modeling piecewise linear objectives and constraints in glpk
From: |
Robbie Morrison |
Subject: |
[Help-glpk] modeling piecewise linear objectives and constraints in glpk |
Date: |
Tue, 23 Dec 2008 18:54:33 +0100 |
User-agent: |
Thunderbird 1.5.0.14ubu (X11/20080306) |
Hello GLPK users
Andrew Makhorin made a posting to this list on 02 June
2007 with the subject line "SOS2 constraints in GLPK".
I typeset this original posting to make the maths more
readable and added an additional note from Andrew
concerning the modeling of constraints as well as
objectives.
The attached PDF should be of interest to anyone
wishing to model piecewise linear objectives and
constraints in GLPK (or any other MIP solver).
Can someone tell me whether 'f(x)' can be be
vector-valued? Or is this formulation limited to
scalar functions? (I think not.)
The method given is similar to the "convex combination
model" in Croxton et al (2002, p4). Although their
treatment also considers (lower) semi-continuous
functions (with "jumps", see wikipedia) as well as
strictly-continuous functions. They also set (x1,y1)
to the origin without loss of generality. (Note also
the small error in fig 2 which is not strictly lower
semi-continuous.)
Details of the attached PDF:
filename : glpk-sos2_02.pdf
size : 87 120 bytes
format : PDF document, version 1.4
author : Robbie Morrison <address@hidden>
pages : 2 x A4
md5sum : 222919f36890aa5ca9eda59687217f8e
Email me if you would like the native ooWriter 2.0
file used to produce this PDF.
Perhaps Xypron would like to put the file on his
unofficial GLPK website (or anyone else for that
matter).
References
Croxton, Keely L, Gendon, Bernard, and Magnanti,
Thomas L. 2002. A comparison of mixed-integer
programming models for non-convex piecewise
linear cost minimization problems. Massachusetts
Institute of Technology Operations Research
Center Working Paper OR 363-02
URI: http://hdl.handle.net/1721.1/5233
PDF: OR-363-02.pdf (712kiB)
with best wishes
Robbie
---
Robbie Morrison
PhD student -- policy-oriented energy system simulation
Technical University of Berlin (TU-Berlin), Germany
University email (redirected) : address@hidden
Webmail (preferred) : address@hidden
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glpk-sos2_02.pdf
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