Planning a Zero-Emission Mixed-Fleet Public Bus System with Minimal Life Cycle Cost

  • Nathalie Frieß
  • Ulrich Pferschy
    • Categories Applications - OR and Management Sciences, Transportation Tags , , , , ,

    The variety of available technology options for the operation of zero-emission bus systems gives rise to the problem of finding an optimal technology decision for bus operators. Among others, overnight charging, opportunity charging and hydrogen-based technology options are frequently pursued technological solutions. As their operating conditions are strongly influenced by the urban context, an optimal … Read more

    A Short Proof of Tight Bounds on the Smallest Support Size of Integer Solutions to Linear Equations

  • Yatharth Dubey
  • Siyue Liu
    • Categories Integer Programming, Other Topics Tags ,

    In this note, we study the size of the support of solutions to linear Diophantine equations $Ax=b, ~x\in\Z^n$ where $A\in\Z^{m\times n}, b\in\Z^n$. We give an asymptotically tight upper bound on the smallest support size, parameterized by $\|A\|_\infty$ and $m$, and taken as a worst case over all $b$ such that the above system has a … Read more

    Global convergence of a BFGS-type algorithm for nonconvex multiobjective optimization problems

  • Leandro Fonseca Prudente
  • D. R. Souza
    • Categories Multi-Criteria Optimization Tags , , , , , ,

    We propose a modified BFGS algorithm for multiobjective optimization problems with global convergence, even in the absence of convexity assumptions on the objective functions. Furthermore, we establish the superlinear convergence of the method under usual conditions. Our approach employs Wolfe step sizes and ensures that the Hessian approximations are updated and corrected at each iteration … Read more

    On the Computation of Restricted Normal Cones

  • Mario Jelitte
    • Categories Constrained Nonlinear Optimization, Nonlinear Optimization, Nonsmooth Optimization Tags , , ,

    Restricted normal cones are of interest, for instance, in the theory of local error bounds, where they have recently been used to characterize the exis- tence of a constrained Lipschitzian error bound. In this paper, we establish rela- tions between two concepts for restricted normals. The first of these concepts was introduced in the late … Read more

    Cutting planes from the simplex tableau for quadratically constrained optimization problems

  • Mustafa Vora
  • Ashutosh Mahajan
    • Categories Cutting Plane Approaches, Global Optimization Tags , ,

    We describe a method to generate cutting planes for quadratically constrained optimization problems. The method uses information from the simplex tableau of a linear relaxation of the problem in combination with McCormick estimators. The method is guaranteed to cut off a basic feasible solution of the linear relaxation that violates the quadratic constraints in the … Read more

    Structured Pruning of Neural Networks for Constraints Learning

  • Matteo Cacciola
  • Andrea Lodi
  • Antonio Frangioni
    • Categories (Mixed) Integer Linear Programming, Combinatorial Optimization, Optimization in Data Science Tags , ,

    In recent years, the integration of Machine Learning (ML) models with Operation Research (OR) tools has gained popularity across diverse applications, including cancer treatment, algorithmic configuration, and chemical process optimization. In this domain, the combination of ML and OR often relies on representing the ML model output using Mixed Integer Programming (MIP) formulations. Numerous studies … Read more

    Sub-Exponential Lower Bounds for Branch-and-Bound with General Disjunctions via Interpolation

  • Max Gläser
  • Marc E. Pfetsch
    • Categories Integer Programming

    This paper investigates linear programming based branch-and-bound using general disjunctions, also known as stabbing planes, for solving integer programs. We derive the first sub-exponential lower bound (in the encoding length \(L\) of the integer program) for the size of a general branch-and-bound tree for a particular class of (compact) integer programs, namely \(2^{\Omega(L^{1/12 -\epsilon})}\) for … Read more

    Inverse Optimization for Routing Problems

  • Pedro Zattoni Scroccaro
  • Peyman Mohajerin Esfahani
  • Bilge Atasoy
    • Categories Applications - OR and Management Sciences, Convex and Nonsmooth Optimization, Transportation

    We propose a method for learning decision-makers’ behavior in routing problems using Inverse Optimization (IO). The IO framework falls into the supervised learning category and builds on the premise that the target behavior is an optimizer of an unknown cost function. This cost function is to be learned through historical data, and in the context … Read more

    Robust Workforce Management with Crowdsourced Delivery

  • Chun Cheng
  • Melvyn Sim
  • Yue Zhao
    • Categories Robust Optimization, Transportation Tags , , ,

    We investigate how crowdsourced delivery platforms with both contracted and ad-hoc couriers can effectively manage their workforce to meet delivery demands amidst uncertainties. Our objective is to minimize the hiring costs of contracted couriers and the crowdsourcing costs of ad-hoc couriers while considering the uncertain availability and behavior of the latter. Due to the complication … Read more

    A Polynomial Algorithm for the Lossless Battery Charging Problem

  • James Ostrowski
    • Categories Applications - Science and Engineering, Energy, Network Optimization Tags , ,

    This study presents a polynomial time algorithm to solve the lossless battery charging problem. In this problem the optimal charging and discharging schedules are chosen to maximize total profit. Traditional solution approaches have relied on either approximations or exponential algorithms. By studying the optimality conditions of this problem, we are able to reduce it to … Read more