Affiliation: | 1. Dipartimento di Scienze, Università degli Studi “G. d’Annunzio”, viale Pindaro 42, 65127 Pescara, Italy;2. Department of Mathematics, Wesleyan University, Middletown, CT 06459, USA;3. Reem-Kayden Center 207, 31 Campus Road, Bard College, Annandale-on-Hudson, NY 12504B, USA |