11,100 research outputs found
Lagrange Duality of Set-Valued Optimization with Natural Criteria
Set optimization problems with objective set-valued maps are considered, and some criteria of solutions are defined. Also, cone lower semicontinuities of set-valued maps are introduced, and existence theorems of solutions of such problems are es-tablished. Moreover, some duality results of these problems are investigated
Existence of Weak Efficient Solutions of Set-Valued Optimization Problems
In this paper, we consider a new scalarization function for set-valued maps.
As the main goal, by using this scalarization function, we obtain some
Weierstrass-type theorems for the noncontinuous set optimization problems via
the coercivity and noncoercivity conditions. This contribution improves various
existing results in the literature
First order optimality condition for constrained set-valued optimization
A constrained optimization problem with set-valued data is considered. Different kind of solutions are defined for such a problem. We recall weak minimizer, efficient minimizer and proper minimizer. The latter are defined in a way that embrace also the case when the ordering cone is not pointed. Moreover we present the new concept of isolated minimizer for set-valued optimization. These notions are investigated and appear when establishing first-order necessary and sufficient optimality conditions derived in terms of a Dini type derivative for set-valued maps. The case of convex (along rays) data is considered when studying sufficient optimality conditions for weak minimizers. Key words: Vector optimization, Set-valued optimization, First-order optimality conditions.
Weak Minimizers, Minimizers and Variational Inequalities for set valued Functions. A blooming wreath?
In the literature, necessary and sufficient conditions in terms of
variational inequalities are introduced to characterize minimizers of convex
set valued functions with values in a conlinear space. Similar results are
proved for a weaker concept of minimizers and weaker variational inequalities.
The implications are proved using scalarization techniques that eventually
provide original problems, not fully equivalent to the set-valued counterparts.
Therefore, we try, in the course of this note, to close the network among the
various notions proposed. More specifically, we prove that a minimizer is
always a weak minimizer, and a solution to the stronger variational inequality
always also a solution to the weak variational inequality of the same type. As
a special case we obtain a complete characterization of efficiency and weak
efficiency in vector optimization by set-valued variational inequalities and
their scalarizations. Indeed this might eventually prove the usefulness of the
set-optimization approach to renew the study of vector optimization
Set-optimization meets variational inequalities
We study necessary and sufficient conditions to attain solutions of
set-optimization problems in therms of variational inequalities of Stampacchia
and Minty type. The notion of a solution we deal with has been introduced Heyde
and Loehne, for convex set-valued objective functions. To define the set-valued
variational inequality, we introduce a set-valued directional derivative and we
relate it to the Dini derivatives of a family of linearly scalarized problems.
The optimality conditions are given by Stampacchia and Minty type Variational
inequalities, defined both by the set valued directional derivative and by the
Dini derivatives of the scalarizations. The main results allow to obtain known
variational characterizations for vector valued optimization problems
Solving ill-posed bilevel programs
This paper deals with ill-posed bilevel programs, i.e., problems admitting multiple lower-level solutions for some upper-level parameters. Many publications have been devoted to the standard optimistic case of this problem, where the difficulty is essentially moved from the objective function to the feasible set. This new problem is simpler but there is no guaranty to obtain local optimal solutions for the original optimistic problem by this process. Considering the intrinsic non-convexity of bilevel programs, computing local optimal solutions is the best one can hope to get in most cases. To achieve this goal, we start by establishing an equivalence between the original optimistic problem an a certain set-valued optimization problem. Next, we develop optimality conditions for the latter problem and show that they generalize all the results currently known in the literature on optimistic bilevel optimization. Our approach is then extended to multiobjective bilevel optimization, and completely new results are derived for problems with vector-valued upper- and lower-level objective functions. Numerical implementations of the results of this paper are provided on some examples, in order to demonstrate how the original optimistic problem can be solved in practice, by means of a special set-valued optimization problem
A recursive algorithm for multivariate risk measures and a set-valued Bellman's principle
A method for calculating multi-portfolio time consistent multivariate risk
measures in discrete time is presented. Market models for assets with
transaction costs or illiquidity and possible trading constraints are
considered on a finite probability space. The set of capital requirements at
each time and state is calculated recursively backwards in time along the event
tree. We motivate why the proposed procedure can be seen as a set-valued
Bellman's principle, that might be of independent interest within the growing
field of set optimization. We give conditions under which the backwards
calculation of the sets reduces to solving a sequence of linear, respectively
convex vector optimization problems. Numerical examples are given and include
superhedging under illiquidity, the set-valued entropic risk measure, and the
multi-portfolio time consistent version of the relaxed worst case risk measure
and of the set-valued average value at risk.Comment: 25 pages, 5 figure
A Convergent Approximation of the Pareto Optimal Set for Finite Horizon Multiobjective Optimal Control Problems (MOC) Using Viability Theory
The objective of this paper is to provide a convergent numerical
approximation of the Pareto optimal set for finite-horizon multiobjective
optimal control problems for which the objective space is not necessarily
convex. Our approach is based on Viability Theory. We first introduce the
set-valued return function V and show that the epigraph of V is equal to the
viability kernel of a properly chosen closed set for a properly chosen
dynamics. We then introduce an approximate set-valued return function with
finite set-values as the solution of a multiobjective dynamic programming
equation. The epigraph of this approximate set-valued return function is shown
to be equal to the finite discrete viability kernel resulting from the
convergent numerical approximation of the viability kernel proposed in [4, 5].
As a result, the epigraph of the approximate set-valued return function
converges towards the epigraph of V. The approximate set-valued return function
finally provides the proposed numerical approximation of the Pareto optimal set
for every initial time and state. Several numerical examples are provided
Stable Recovery Of Sparse Vectors From Random Sinusoidal Feature Maps
Random sinusoidal features are a popular approach for speeding up
kernel-based inference in large datasets. Prior to the inference stage, the
approach suggests performing dimensionality reduction by first multiplying each
data vector by a random Gaussian matrix, and then computing an element-wise
sinusoid. Theoretical analysis shows that collecting a sufficient number of
such features can be reliably used for subsequent inference in kernel
classification and regression.
In this work, we demonstrate that with a mild increase in the dimension of
the embedding, it is also possible to reconstruct the data vector from such
random sinusoidal features, provided that the underlying data is sparse enough.
In particular, we propose a numerically stable algorithm for reconstructing the
data vector given the nonlinear features, and analyze its sample complexity.
Our algorithm can be extended to other types of structured inverse problems,
such as demixing a pair of sparse (but incoherent) vectors. We support the
efficacy of our approach via numerical experiments
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