A mechanism of function calls in MSVL

Modeling, Simulation and Verification Language (MSVL) is a useful formalism for specification and verification of concurrent systems. To make it more practical and easier to use, we extend MSVL with external and internal function calls. To do so, the syntax of function definitions and function calls is formalized. Then, the syntax of expressions in MSVL is extended by including function calls. Further, the evaluation rules are redefined. Moreover, the set of statements in MSVL is also extended and the semantics of function call statements is formalized. In addition, the existence of minimal models of MSVL programs involving new added statements is proved. Finally, an example is given to illustrate how to interpret function calls in practice with MSVL.