Abstract
We formalize in Isabelle/HOL the abtract syntax and a synchronous
step semantics for the specification language Statecharts. The formalization
is based on Hierarchical Automata which allow a structural decomposition of
Statecharts into Sequential Automata. To support the composition of
Statecharts, we introduce calculating operators to construct a Hierarchical
Automaton in a stepwise manner. Furthermore, we present a complete semantics
of Statecharts including a theory of data spaces, which enables the modelling
of racing effects. We also adapt CTL for
Statecharts to build a bridge for future combinations with model
checking. However the main motivation of this work is to provide a sound and
complete basis for reasoning on Statecharts. As a central meta theorem we
prove that the well-formedness of a Statechart is preserved by the semantics.