Communicating TILCO: a Model for Real-Time System Specification

Formal techniques for the specification of real-time systems must be capable of describing a set of relationships expressing the temporal constraints among events and actions: properties of invariance, precedence, periodicity, liveness and safety conditions, etc. This paper describes CTILCO, an extension of TILCO (Temporal Interval Logic with Compositional Operators). CTILCO introduces the Communication among components specified in TILCO and allows the adoption of decomposition/composition mechanisms. TILCO has been expressly designed for the specification of realtime systems. CTILCO is based on time intervals and can concisely express temporal constraints with time bounds, such as those needed to specify real-time systems. It can be used to verify the completeness and consistency of specifications, as well as to validate system behavior against its requirements and general properties. CTILCO has been formalized by using the theorem prover Isabelle/HOL. CTILCO specifications satisfying certain properties are executable. CTILCO is defined in terms of theorems and allows the system specification and the formal proof of properties including composition/decomposition with communications. An example of system specification and validation has been also included.