Foundations of Software Science and Computation Structures 4th International Conference, FOSSACS 2001 Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2001 Genova, Italy, April 2-6, 2001, Proceedings - Honsell, Furio; Honsell, Furio; Miculan, Marino; Miculan, Marino (Springer Berlin Heidelberg : Imprint: Springer, 2001)