A Graph Reduction Heuristic For Supply Chain Transportation Plan Optimization

International audience; We address to a problem of freight transportation in supply chains. To model flows over time in the system, we use time-expanded graphs. However, the time-expanded graphs' size increases exponentially with the number of actors and the time dimension, which makes the industrial solvers inefficient to overcome real instances. To face this difficulty, we conceived an heuristic based from Boland's and Hewitt's Dynamic Discretization Discovery. We manipulates a partially time-expanded graph, componed of a small subset of nodes and arcs, and enriches it incrementally. We produce a sparse graph with the essential elements and solve the associated problem, with much less constraints and variables.