12 research outputs found
Projections in minimax algebra
An axiomatic theory of linear operators can be constructed for abstract spaces defined over (R, ⊕, ⊗), that is over the (extended) real numbersR with the binary operationsx ⊕ y = max (x,y) andx ⊗ y = x + y. Many of the features of conventional linear operator theory can be reproduced in this theory, although the proof techniques are quite different. Specialisation of the theory to spaces ofn-tuples provides techniques for analysing a number of well-known operational research problems, whilst specialisation to function spaces provides a natural formal framework for certain familiar problems of approximation, optimisation and duality
Direct solutions to tropical optimization problems with nonlinear objective functions and boundary constraints
We examine two multidimensional optimization problems that are formulated in
terms of tropical mathematics. The problems are to minimize nonlinear objective
functions, which are defined through the multiplicative conjugate vector
transposition on vectors of a finite-dimensional semimodule over an idempotent
semifield, and subject to boundary constraints. The solution approach is
implemented, which involves the derivation of the sharp bounds on the objective
functions, followed by determination of vectors that yield the bound. Based on
the approach, direct solutions to the problems are obtained in a compact vector
form. To illustrate, we apply the results to solving constrained Chebyshev
approximation and location problems, and give numerical examples.Comment: Mathematical Methods and Optimization Techniques in Engineering:
Proc. 1st Intern. Conf. on Optimization Techniques in Engineering (OTENG
'13), Antalya, Turkey, October 8-10, 2013, WSEAS Press, 2013, pp. 86-91. ISBN
978-960-474-339-
Generators, extremals and bases of max cones
Max cones are max-algebraic analogs of convex cones. In the present paper we
develop a theory of generating sets and extremals of max cones in . This theory is based on the observation that extremals are minimal
elements of max cones under suitable scalings of vectors. We give new proofs of
existing results suitably generalizing, restating and refining them. Of these,
it is important that any set of generators may be partitioned into the set of
extremals and the set of redundant elements. We include results on properties
of open and closed cones, on properties of totally dependent sets and on
computational bounds for the problem of finding the (essentially unique) basis
of a finitely generated cone.Comment: 15 pages, 1 figure; v2: new layout, several new references,
renumbering of result
A constrained tropical optimization problem: complete solution and application example
The paper focuses on a multidimensional optimization problem, which is
formulated in terms of tropical mathematics and consists in minimizing a
nonlinear objective function subject to linear inequality constraints. To solve
the problem, we follow an approach based on the introduction of an additional
unknown variable to reduce the problem to solving linear inequalities, where
the variable plays the role of a parameter. A necessary and sufficient
condition for the inequalities to hold is used to evaluate the parameter,
whereas the general solution of the inequalities is taken as a solution of the
original problem. Under fairly general assumptions, a complete direct solution
to the problem is obtained in a compact vector form. The result is applied to
solve a problem in project scheduling when an optimal schedule is given by
minimizing the flow time of activities in a project under various activity
precedence constraints. As an illustration, a numerical example of optimal
scheduling is also presented.Comment: 20 pages, accepted for publication in Contemporary Mathematic
Algebraic solutions of tropical optimization problems
We consider multidimensional optimization problems, which are formulated and
solved in terms of tropical mathematics. The problems are to minimize
(maximize) a linear or nonlinear function defined on vectors of a
finite-dimensional semimodule over an idempotent semifield, and may have
constraints in the form of linear equations and inequalities. The aim of the
paper is twofold: first to give a broad overview of known tropical optimization
problems and solution methods, including recent results; and second, to derive
a direct, complete solution to a new constrained optimization problem as an
illustration of the algebraic approach recently proposed to solve tropical
optimization problems with nonlinear objective function.Comment: 25 pages, presented at Intern. Conf. "Algebra and Mathematical Logic:
Theory and Applications", June 2-6, 2014, Kazan, Russi
マックスプラス代数のスケジューリング問題への応用
学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 西成 活裕, 東京大学教授 太田 順, 東京大学教授 時弘 哲治, 東京大学准教授 白石 潤一, 東京大学准教授 柳澤 大地University of Tokyo(東京大学