Andrea Tramontani

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Disjunctive cuts for Mixed-Integer Linear Programs have been introduced by Egon Balas in the late 70's, and successfully exploited in practice since the late 90's. In this paper we investigate the main ingredients of a disjunctive cut separation procedure, and analyze their impact on the quality of the root-node bound for a set of instances taken from(More)
We address the Open Vehicle Routing Problem (OVRP), a variant of the ''classical'' (capacitated and distance constrained) Vehicle Routing Problem (VRP) in which the vehicles are not required to return to the depot after completing their service. We present a heuristic improvement procedure for OVRP based on Integer Linear Programming (ILP) techniques. Given(More)
Following the flurry of recent theoretical work on cutting planes from two-row mixed integer group relaxations of an LP tableau, we report on computational tests to evaluate the strength of two-row cuts based on lattice-free triangles having more than one integer point on one side. A heuristic procedure to generate such triangles (referred to in the(More)
The Traveling Salesman Problem with Time Windows (TSPTW) is the problem of finding a minimum-cost path visiting a set of cities exactly once, where each city must be visited within a given time window. We present an extended formulation for the problem based on partitioning the time windows into sub-windows, which we call buckets. We present cutting planes(More)