We study the Regularized A-Optimal Design (RAOD) problem, which selects a subset of \(k\) experiments to minimize the inverse of the Fisher information matrix, regularized with a scaled identity matrix. RAOD has broad applications in Bayesian experimental design, sensor placement, and cold-start recommendation. We prove its NP-hardness via a reduction from the independent set problem. … Read more
We address the Undirected Team Orienteering Arc Routing Problem (UTOARP). In this problem, demand is placed at some edges of a given undirected graph and served demand edges produce a profit. Feasible routes must start and end at a given depot and there is a time limit constraint on the maximum duration of each route. … Read more
Positive spanning sets (PSSs) are families of vectors that span a given linear space through non-negative linear combinations. Despite certain classes of PSSs being well understood, a complete characterization of PSSs remains elusive. In this paper, we explore a relatively understudied relationship between positive spanning sets and strongly edge-connected digraphs, in that the former can … Read more
In this work, we present the first 2-index stage-based formulation for the Flying Sidekick Traveling Salesman Problem (FSTSP). Additionally, we propose a Construct-Merge-Solve & Adapt (CMSA) algorithm designed to generate high-quality feasible solutions. Experimental results demonstrate that the proposed algorithm consistently produces good solutions in a fraction of the time required by state-of-the-art mixed-integer linear … Read more
The Lovasz theta function is a semidefinite programming (SDP) relaxation for the maximum weighted stable set problem, which is tight for perfect graphs. However, even for perfect graphs, there is no known rounding method guaranteed to extract an optimal stable set from the SDP solution. In this paper, we develop a novel rounding scheme for … Read more
We derive practical stability results for finite-control set and mixed-integer model predictive control. Thereby, we investigate the evolution of the closed-loop system in the presence of control rounding and draw conclusions about optimality. The paper integrates integral approximation strategies with the inherent robustness properties of conventional model predictive control with stabilizing terminal conditions. We propose … Read more
A Surgery Pre-Admission Testing (PAT) clinic is a hospital unit designed to serve pre-operative patients by gathering critical patient information and performing procedure-specific tests to prepare them for surgery. Patients may require multiple tests, each conducted by a specialized nurse. A patient must be assigned to a room before starting any test and must stay … Read more
Problem definition: More than one-third of US domestic flights are operated by regional airlines. This paper focuses on optimizing medium-term schedule planning decisions for a network of regional airlines through the joint optimization of frequency planning, timetable development, fleet assignment, and some limited aspects of route planning, while capturing passengers’ travel decisions through a general … Read more
The kidney exchange problem with reserve arcs (KEP-RA) is an extension of the classical kidney exchange problem in which one is allowed to select in the solution a limited number of arcs that do not belong to the compatibility graph. This problem is motivated by recent breakthroughs in the field of kidney transplantation involving immunosuppressants … Read more
In this paper, a class of bilevel programming problems is studied, in which the lower level is a quadratic programming problem, and the upper level problem consists of a nonlinear objective function with coupling constraints. An iterative process is developed to generate a sequence of points, which converges to the solution of this problem. In … Read more