Specification Problem

The problem calls for the specification and verification of a series of components. Components interact with one another using a procedure-calling interface. One component issues a call to another, and the second component responds by issuing a return. A call is an indivisible (atomic) action that communicates a procedure name and a list of arguments to the called component. A return is an atomic action issued in response to a call. There are two kinds of returns, normal and exceptional. A normal call returns a value (which could be a list). An exceptional return also returns a value, usually indicating some error condition. An exceptional return of a value e is called raising exception e. A return is issued only in response to a call. There may be “syntactic” restrictions on the types of arguments and return values. A component may contain multiple processes that can concurrently issue procedure calls. More precisely, after one process issues a call, other processes can issue calls to the same component before the component issues a return from the first call. A return action communicates to the calling component the identity of the process that issued the corresponding call.