µ-Charts and Z: Extending the translation

Abstract

This paper describes extensions and modifications to the µ-charts as given in earlier papers of Philipps and Scholz. The charts are extended to include a command language, integer-valued signals and local integer variables. The command language is based on the syntax presented in Scholz’ thesis and the integer-valued signals and local variables are based loosely on Scholz’ earlier work. After presenting the new semantics we turn to extending the µ-charts-to-Z translation that we developed in previous work. The extensions to the translation process describe both the changes due to the extensions to the µ-charts and a modification to the translation method to more fully capture the beneficial modularisation encouraged by the µ-charts formalism. We finish by giving three complete translation examples. The paper should be read as a record of our gradual development of a Z semantics for µ-charts–hence its sometimes exploratory character or laborious explanations as we come to terms (thinking out loud) with the (sometimes very subtle) meaning of µ-charts, especially with regard to pathological and unusual examples of their use.