Logic and refinement for charts

We introduce a logic for reasoning about and constructing refinements for µ-Charts, a rational simplification and reconstruction of Statecharts. The method of derivation of the logic is that a semantics for the language is constructed in Z and the existing logic and refinement calculus of Z is then used to induce the logic and refinement calculus of µ-Charts, proceeding by a series of definitions and conservative extensions and hence generating a sound logic for µ-Charts, given that the soundness of the Z logic has already been established.