Category Theory and Computer Science : 7th International Conference CTCS 97 Santa Margherita Ligure Italy September 4 6 1997 Proceedings This book constitutes the refereed proceedings of the 7th International Conference on Category Theory and Computer Science CTCS97 held in Santa Margheria Ligure Italy in September 1997. Category theory attracts interest in the theoretical computer science community because of its ability to establish connections between different areas in computer science and mathematics and to provide a few generic principles for organizing mathematical theories. This book presents a selection of 15 revised full papers together with three invited contributions. The topics addressed include reasoning principles for types rewriting program semantics and structuring of logical systems