This book constitutes the refereed proceedings of FME '97, the 4th International Symposium of Formal Methods Europe devoted to Industrial Applications and Strengthened Foundations of Formal Methods , held in Graz, Austria, in September 1997. The 35 revised full papers presented in the volume were selected from a total of 94 submissions. Formal methods and mathematically based techniques are increasingly recognized as a viable technology for the development and engineering of computing systems. The majority of the papers in this volume describe industrial applications, extensions to existing techniques, or case studies, papers on theoretical aspects show clear potential applicability.