09h00 - 09h25
Periodic Vehicle Routing Problem with Time Spread Constraints on Services
Security constraints are rarely considered in vehicle routing. We will focus on the periodic transportation of valuable goods. Delivery schedules must be unpredictable in order to make any potential attack difficult to plan. We present an effective MS-ILS approach to deal with real world problems.
09h25 - 09h50
Real-Time Optimization of Reactive Technician Tours
We consider a vehicle routing problem with multiple depots, time windows, priority within customers and stochastic travel and service times. To tackle this problem, we propose a three step method consisting in establishing a skeleton of urgent customers, in inserting non urgent customers in this skeleton and finally in modifying the planning in real time (to face stochasticity on travel and service times) by removing some non urgent customers.
09h50 - 10h15
A Branch-and-Cut-and-Price Algorithm for a Rich Vehicle Routing Problem with Vehicle Transfers Between Depots
We introduce a rich vehicle routing problem with multiple depots. With each depot is assigned a
set of customers that can be reached from vehicles departing at that depot. With each customer is
associated a time window in which service can take place. We consider a prize-collection version
of the problem in which some customers can be left without service due to feasibility/cost
reasons. Vehicles associated to some depot can be transferred to another to increase demand
covering and thus decrease costs. The problem is formulated as a set-partitioning problem and
solved by means of column generation. Several classes of valid inequalities are used to strengthen the formulation. Preliminary computational results will be presented.
10h15 - 10h40
On Generalizations of the Miller-Tucker-Zemlin and Desrochers and Laporte Constraints
In this talk, we present generalizations of the Miller-Tucker-Zemlin (MTZ) and Desrochers and Laporte (DL) constraints. We start by showing that these constraints could have been obtained by examining 2-node set polyhedron. We generalize the same approach for 3-node sets in order to obtain the generalized inequalities. We give some evidence that the approach may not be easily extended for 4-node sets.