| Citation | David Harel has contributed enormously to many areas of computer science. Perhaps most significant are his groundbreaking contributions to software and systems engineering. He defined and/or promoted key concepts - model-based development, reactive systems, executable specifications, code-generation, visual formalisms, state-based and scenario-based programming, and play-in/out. He invented the ingeniously intuitive visual languages of Statecharts and Live Sequence Charts and their supporting tools. This work has had unparalleled impact on research and real-world practice, constituting a transformative contribution to one of the most difficult and crucial activities of the computer era: building reliable complex systems. As well as software engineering he has also made fundamental and highly influential contributions to logics of programs, databases, computability, automata theory and modelling biological systems. |