Alberto Colorni

Alberto Colorni, Alexis Tsoukiàs

This paper presents a general framework about what is a decision problem. Our motivation is related to the fact that decision analysis and operational research are structured (as disciplines) around classes of methods, while instead we should first characterise the decision problems our clients present us. For this purpose we introduce a new framework, independent from any existing method, based upon primitives provided by (or elicited from) the client. We show that the number of archetypal decision problems are finite and so the archetypal decision support methods.

Maurizio Bruglieri, Alberto Colorni, Alessandro Luè

Traditional car-sharing services are based on the two-way scheme, where the user picks up and returns the vehicle at the same parking station. Some services permits also one-way trips, which allows the user to return the vehicle in another station. The one-way scheme is quite more attractive for the users, but may pose a problem for the distribution of the vehicles, due to a possible unbalancing between the user demand and the availability of vehicles or free slots at the stations. Such a problem is more complicated in the case of electrical car sharing, where the travel range depends on the level of charge of the vehicles. The paper presents a new approach for the Electric Vehicle Relocation Problem, where cars are moved by personnel of the service operator to keep the system balanced. Such a problem generates a challenging pickup and delivery problem with new features that to the best of our knowledge never have been considered in the literature. We yield a Mixed Integer Linear Programming formulation and some valid inequalities to speed up its solution through a state-of-the art solver (CPLEX). We test our approach on verisimilar instances built on the Milan road network.