In memoriam of professor Guenther Ruhe: Contributions to the software product management research and practice

For many years, Guenther Ruhe was a fellow of the International Software Product Management Association, playing an important role in shaping the academic and practical landscapes of Software Product Management (SPM). This editorial note honors Ruhe's enduring impact on the SPM Body of Knowledge, evaluating his extensive contributions to SPM research and practice, and recognizing his legacy in shaping the future trajectory of the field. By examining Ruhe's academic publications and his role in developing the SPM Body of Knowledge, we highlight key areas of his influence, particularly in release planning and requirements engineering. His integration of empirical research into SPM has notably enhanced the discipline's rigor and relevance. Ruhe's contributions to the SPM Body of Knowledge are profound and far-reaching, establishing his work as a cornerstone for ongoing research and practice in SPM.