  This report documents the program and results of the GI-Dagstuhl Seminar
19023 on Explainable Software for Cyber-Physical Systems (ES4CPS). The seminar
was concerned with the challenge that for future Cyber-Physical Systems (CPS),
it will become increasingly relevant to explain their behavior (past, current,
and future behavior, why a certain action was taken, how a certain goal can be
achieved, etc.) to users, engineers, and other stakeholders. In order to
increase the explainability of CPS and their engineering tools, fundamental,
interdisciplinary research is required; solutions from multiple disciplines
within software engineering, systems engineering, and related fields have to be
applied, combined, and researched further. The goal of this seminar was to
serve as a starting point for an interdisciplinary coordination of research
activities targeting ES4CPS and an incubator of a new research community around
this topic.
