Affiliation: | 1.Department of Mathematical Sciences “G.L. Lagrange”, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy ;2.Department of Mathematics, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy ;3.MOX-Politecnico di Milano, Piazza Leonardo da Vinci 23, 20133, Milan, Italy ; |