Adjustable robust optimization for fleet sizing problem in closed-loop supply chains with simultaneous delivery and pickup

  • Ali Borumand
  • Ali Nookabadi
    • Categories (Mixed) Integer Linear Programming, Meta Heuristics, Robust Optimization Tags , , , ,

    The Fleet Sizing Problem (FSP) stands as a critical challenge within the realm of logistics and supply chain management, particularly in the context of Closed-Loop Supply Chains (CLSC). The significance of addressing the FSP lies in its direct impact on operational costs, resource utilization, and environmental sustainability. By effectively optimizing fleet size, organizations can streamline … Read more

    Fourth-order Marginal Moment Model: Reformulations and Applications

  • Mingyang FU
  • Xiaobo Li
    • Categories Applications - OR and Management Sciences, Combinatorial Optimization, Robust Optimization Tags , , , , ,

    This paper investigates the bounds on the expectation of combinatorial optimization given moment information for each individual random variable. A popular approach to solving this problem, known as the marginal moment model (MMM), is to reformulate it as a semidefinite program (SDP). In this paper, we investigate the structure of MMM with up to fourth-order … Read more

    The SCIP Optimization Suite 9.0

  • Suresh Bolusani
  • Mathieu Besançon
  • Ksenia Bestuzheva
  • Antonia Chmiela
  • João Dionísio
  • Tim Donkiewicz
  • Jasper van Doornmalen
  • Leon Eifler
  • Mohammed Ghannam
  • Ambros Gleixner
  • Christoph Graczyk
  • Katrin Halbig
  • Ivo Hedtke
  • Alexander Hoen
  • Christopher Hojny
  • Rolf van der Hulst
  • Dominik Kamp
  • Thorsten Koch
  • Kevin Kofler
  • Jurgen Lentz
  • Julian Manns
  • Gioni Mexi
  • Erik Mühmer
  • Marc E. Pfetsch
  • Franziska Schlösser
  • Felipe Serrano
  • Yuji Shinano
  • Mark Turner
  • Stefan Vigerske
  • Dieter Weninger
  • Liding Xu
    • Categories Integer Programming, Linear, Cone and Semidefinite Programming, Optimization Software and Modeling Systems Tags , , , , , , , , ,

    The SCIP Optimization Suite provides a collection of software packages for mathematical optimization, centered around the constraint integer programming (CIP) framework SCIP. This report discusses the enhancements and extensions included in the SCIP Optimization Suite 9.0. The updates in SCIP 9.0 include improved symmetry handling, additions and improvements of nonlinear handlers and primal heuristics, a … Read more

    Distributed Task Assignment in a Swarm of UAVs

  • Luigi Bobbio
  • Jörg Fliege
  • Antonio Martinez-Sykora
    • Categories (Mixed) Integer Linear Programming, Applications - OR and Management Sciences, Scheduling

    We consider the problem of distributed task assignment in a swarm of Unmanned Aerial Vehicles (UAVs), where heterogeneous agents that can have different capabilities need to work in teams to execute tasks. We consider the case where communication between UAVs is costly or dangerous and should be limited or avoided, while individual UAVs have uncertain … Read more

    Set System Approximation for Binary Integer Programs: Reformulations and Applications

  • Ningji Wei
    • Categories 0-1 Programming, Cutting Plane Approaches, Integer Programming Tags , , , ,

    Covering and elimination inequalities are central to combinatorial optimization, yet their role has largely been studied in problem-specific settings or via no-good cuts. This paper introduces a unified perspective that treats these inequalities as primitives for set system approximation in binary integer programs (BIPs). We show that arbitrary set systems admit tight inner and outer … Read more

    On Averaging and Extrapolation for Gradient Descent

  • Alan Luner
  • Benjamin Grimmer
    • Categories Convex Optimization, Semi-definite Programming Tags , , , ,

    This work considers the effect of averaging, and more generally extrapolation, of the iterates of gradient descent in smooth convex optimization. After running the method, rather than reporting the final iterate, one can report either a convex combination of the iterates (averaging) or a generic combination of the iterates (extrapolation). For several common stepsize sequences, … Read more

    On Coupling Constraints in Linear Bilevel Optimization

  • Dorothee Henke
  • Henri Lefebvre
  • Martin Schmidt
  • Johannes Thürauf
    • Categories (Mixed) Integer Linear Programming, Complementarity and Variational Inequalities, Other Topics Tags ,

    It is well-known that coupling constraints in linear bilevel optimization can lead to disconnected feasible sets, which is not possible without coupling constraints. However, there is no difference between linear bilevel problems with and without coupling constraints w.r.t. their complexity-theoretical hardness. In this note, we prove that, although there is a clear difference between these … Read more

    Problem-Parameter-Free Decentralized Nonconvex Stochastic Optimization

  • Jiaxiang Li
  • Xuxing Chen
  • Shiqian Ma
  • Mingyi Hong
    • Categories Nonlinear Optimization, Stochastic Programming

    Existing decentralized algorithms usually require knowledge of problem parameters for updating local iterates. For example, the hyperparameters (such as learning rate) usually require the knowledge of Lipschitz constant of the global gradient or topological information of the communication networks, which are usually not accessible in practice. In this paper, we propose D-NASA, the first algorithm … Read more

    A new proximal gradient algorithm for solving mixed variational inequality problems with a novel explicit stepsize and applications

  • Pham Thi Hoai
    • Categories Complementarity and Variational Inequalities, Convex Optimization, Nonlinear Optimization Tags , , , ,

    In this paper, we propose a new algorithm for solving monotone mixed variational inequality problems in real Hilbert spaces based on proximal gradient method. Our new algorithm uses a novel explicit stepsize which is proved to be increasing to a positive value. This property plays an important role in improving the speed of the algorithm. … Read more