Agent Systems Mobile Agents and Applications : Second International Symposium on Agent Systems and Applications and Fourth International Symposium on Mobile Agents ASA MA 2000 Zurich Switzerland September 13 15 2000 Proceedings This book constitues the refereed proceedings of the Second International Symposium on Agent Systems and Applications and the Fourth International Symposium on Mobile Agents ASA MA 2000 held in Zürich Switzerland in September 2000. The 20 revised full papers presented were carefully reviewed and selected from 107 submissions. The papers are organized in topical sections on migration security issues systems and applications mobile agent applications applications of multi agent systems communication and mobility control cooperation and interaction