Pedro Munari

The robust vehicle routing problem with time windows: compact formulation and branch-price-and-cut method

  • Douglas Alem
  • Jonathan De La Vega
  • Jacek Gondzio
  • Reinaldo Morabito
  • Pedro Munari
  • Alfredo Moreno
    • Categories Applications - OR and Management Sciences, Robust Optimization, Transportation

    We address the robust vehicle routing problem with time windows (RVRPTW) under customer demand and travel time uncertainties. As presented thus far in the literature, robust counterparts of standard formulations have challenged general-purpose optimization solvers and specialized branch-and-cut methods. Hence, optimal solutions have been reported for small-scale instances only. Additionally, although the most successful methods … Read more

    A Branch-and-Benders-Cut Algorithm for the Road Restoration Crew Scheduling and Routing Problem

  • Douglas Alem
  • Pedro Munari
  • Alfredo Moreno
    • Categories Applications - OR and Management Sciences, Branch and Cut Algorithms, Cutting Plane Approaches Tags , , , ,

    Extreme events such as disasters cause partial or total disruption of basic services such as water, energy, communication and transportation. In particular, roads can be damaged or blocked by debris, thereby obstructing access to certain affected areas. Thus, restoration of the damaged roads is necessary to evacuate victims and distribute emergency commodities to relief centers … Read more

    Robust Optimization for the Vehicle Routing Problem with Multiple Deliverymen

  • Jonathan De La Vega
  • Reinaldo Morabito
  • Pedro Munari
    • Categories Applications - OR and Management Sciences, Production and Logistics, Transportation Tags , , ,

    This paper studies the vehicle routing problem with time windows and multiple deliverymen in which customer demands are uncertain and belong to a predetermined polytope. In addition to the routing decisions, this problem aims to define the number of deliverymen used to provide the service to the customers on each route. A new mathematical formulation … Read more

    An exact hybrid method for the vehicle routing problem with time windows and multiple deliverymen

  • Aldair Álvarez
  • Pedro Munari
    • Categories Combinatorial Optimization, Transportation

    The vehicle routing problem with time windows and multiple deliverymen (VRPTWMD) is a variant of the vehicle routing problem with time windows in which service times at customers depend on the number of deliverymen assigned to the route that serves them. Hence, in addition to the usual routing and scheduling decisions, the crew size for … Read more

    A branch-price-and-cut algorithm for the vehicle routing problem with time windows and multiple deliverymen

  • Reinaldo Morabito
  • Pedro Munari
    • Categories Combinatorial Optimization, Integer Programming, Transportation Tags , , , , , ,

    We address a variant of the vehicle routing problem with time windows (VRPTW) that includes the decision of how many deliverymen should be assigned to each vehicle. In this variant, the service time at each customer depends on the size of the respective demand and on the number of deliverymen assigned to visit this customer. … Read more

    Pickup and delivery problem with time windows: a new compact two-index formulation

  • Maria Gabriela S. Furtado
  • Reinaldo Morabito
  • Pedro Munari
    • Categories Combinatorial Optimization, Integer Programming, Transportation

    We propose a formulation for the pickup and delivery problem with time windows, based on a novel modeling strategy that allows the assignment of vehicles to routes explicitly in two-index flow formulations. It leads to an effective compact formulation that can benefit OR practitioners interested in solving the problem by general-purpose optimization software. Computational experiments … Read more

    Large-scale optimization with the primal-dual column generation method

  • Jacek Gondzio
  • Pedro Munari
  • Pablo Gonzalez-Brevis
    • Categories Convex Optimization, Linear Programming, Optimization Software and Modeling Systems Tags , , , , , ,

    The primal-dual column generation method (PDCGM) is a general-purpose column generation technique that relies on the primal-dual interior point method to solve the restricted master problems. The use of this interior point method variant allows to obtain suboptimal and well-centered dual solutions which naturally stabilizes the column generation. A reduction in the number of calls … Read more

    Using the primal-dual interior point algorithm within the branch-price-and-cut method

  • Jacek Gondzio
  • Pedro Munari
    • Categories Integer Programming Tags , , ,

    Branch-price-and-cut has proven to be a powerful method for solving integer programming problems. It combines decomposition techniques with the generation of both columns and valid inequalities and relies on strong bounds to guide the search in the branch-and-bound tree. In this paper, we present how to improve the performance of a branch-price-and-cut method by using … Read more

    New developments in the primal-dual column generation technique

  • Jacek Gondzio
  • Pedro Munari
  • Pablo Gonzalez-Brevis
    • Categories Combinatorial Optimization, Integer Programming, Linear Programming Tags , ,

    The classical column generation is based on optimal solutions of the restricted master problems. This strategy frequently results in an unstable behaviour and may require an unnecessarily large number of iterations. To overcome this weakness, variations of the classical approach use interior points of the dual feasible set, instead of optimal solutions. In this paper, … Read more