Research Article
A New Technique for Determining Approximate
Center of a Polytope
Syed Inayatullah , Maria Aman, Asma Rani, Hina Zaheer, and Tanveer Ahmed Siddiqi
Department of Mathematics, University of Karachi, Karachi 75270, Pakistan
Correspondence should be addressed to Syed Inayatullah; inayat@uok.edu.pk
Received 5 March 2019; Revised 19 June 2019; Accepted 23 June 2019; Published 15 November 2019
Academic Editor: Imed Kacem
Copyright © 2019 Syed Inayatullah et al. is is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
In this article, we have presented a method for finding the approximate center of a linear programming polytope. is method
provides a point near the center of a polytope in few simple and easy steps. Geometrical interpretation and some numerical
examples have also been presented to demonstrate the proposed approach and comparison of quality of the center obtained by
using the new method with existing methods of finding exact and approximate centers. At the end, we also presented com-
putational results on the randomly generated polytopes to compare the quality of the center obtained by using the new method.
1.Introduction
Linear programming (LP) is a mathematical technique for
optimizing a linear function subject to a set of linear con-
straints and nonnegativity restrictions. Linear programs
frequently show up in various areas of applied sciences
today. e prime reason for this is their manageable,
enormous impact in various disciplines; it has become a core
research area of many mathematicians, economists, decision
scientists, etc. Linear programming was developed during
World War II, when a system with which to maximize the
efficiency of resources was of utmost importance. Since then,
many researchers have strived to advance their ideas and
made centering of the polytope as a core step in the major
optimization techniques (named as interior point methods)
in science and industry.
2.DefinitionsoftheCenterofaPolytope
ere are several ways to define the center of a polytope, it
may be the center of gravity i.e., centroid, mean position of
all vertices i.e., vertex centroid, point at the location where
product of distances from all boundary lines is maximized
i.e., analytic center, center of the least volume ellipsoid that
contains the polytope, or the center of the biggest ball
inside the polytope. erefore, the center of a polytope
depends on the definition we are using. But, fortunately, all
those definitions are equivalent in the sense that, as shown
in [1], if we get a polynomial time algorithm for a center of a
polytope, then that algorithm could also be used to con-
struct a polynomial time algorithm for solving linear
program.
Many techniques [2–4] are used for finding the center of
a polytope, but they are taking so many iterations, slow in
convergence, and require mostly complex computations.
Most of the interior point methods for solving LPs
depend on the computations of a center finding method,
either explicitly or implicitly [3, 5].
e analytic center [6–12] is no doubt the most used
notion of center of a polytope in linear optimization because
of its easy computation, but its disadvantage is that it can be
pushed near the boundary of the polytope by using re-
dundant constraints because its position depends on the
spatial positions of the half-spaces that define the polytope.
So in that case, analytic center may not look like located at a
good central position (see also Section 3). e P-center [3],
also to be discussed in Section 4, provides a much better
center than the analytic center, but it is found in practice that
it takes much longer time to obtain a good approximation of
the P-center.
Hindawi
Advances in Operations Research
Volume 2019, Article ID 8218329, 7 pages
https://doi.org/10.1155/2019/8218329