Introduction to Set Theory and Topology. Kazimierz Kuratowski. Translated from the revised Polish edition by Leo F. Boron. Pergamon, London, 1961; Addison-Wesley, Reading, Mass., 1962. 283 pp. Illus. $6.50
Set theory, category theory, and topology. Pierre Schapira explores the concept of identity within category theory, and what it means for the properties to be satisfied only up to homotopy.