The intuitionism behind statecharts steps

The semantics of Statecharts macro steps, as introduced by Pnueli and Shalev [1991], lacks compositionality. This article first analyzes the compositionality problem and traces it back to the invalidity of the Law of the Excluded Middle. It then characterizes the semantics via a particular class of linear intuitionistic Kripke models. This yields, for the first time in the literature, a simple fully abstract semantics that interprets Pnueli and Shalev's concept of failure naturally. The results not only give insight into the semantic subtleties of Statecharts, but also provide a basis for an implementation, for developing algebraic theories for macro steps, and for comparing different Statecharts variants.