Really visual temporal reasoning

Real-Time Future Interval Logic (RTFIL) is a visual logic with formull that resemble timing diagrams. It is a dense real-time temporal logic that is based on two simple temporal primitives: interval modalities for the purely qualitative part and duration predicates for the quantitative part. In this paper we present the logic, and illustrate its use in specifying the railroad crossing example and proving some of its properties. The logic in its propositional form is decidable by reduction to the emptiness problem of Timed BB uchi Automata. A theorem prover, based on this decision procedure, has been implemented as part of a graph-ical proof environment. The proofs of the railroad crossing example have been veriied using this theorem prover. The combination of an automated theorem prover and a graphical speciication language greatly facilitate the task of verifying real-time proofs. This convenience apart, RT-FIL is invariant under real-time stuttering and does not admit instantaneous states. These properties are expected to facilitate proof methods based on abstraction and re-nement.