Resumen de Comments on: Perspectives on integer programming for time-dependent models 2

Gianpaolo Ghiani, Emanuela Guerriero

• This paper presents an updated and comprehensive review of discrete optimization techniques for solving time-dependent problems, i.e. decision problems in which activities and resources have to be scheduled over time. Known compact models with continuous variables representing arrival/service/departure times are either (i) nonlinear or (ii) linear with a weak relaxation. This is why practitioners (and a consistent part of the scientific literature) make use of a discretization of time which introduces an approximation. Such extended Integer Programming (IP) formulations rely on binary variables indexed by time (time-indexed models, TI). Their size may be huge, and so they tend to be out of reach for the current IP solver technology.