Deadlines are termination

We have recently extended the sequential reenement calculus to handle real-time programs. A novel deadline command allows execution time limits to be expressed in a high-level language. The calculus allows reenement steps that separate timing constraints from non-timing requirements. Rules are provided for handling timing constraints, but the reenement of components implementing non-timing requirements is essentially the same as in the standard reenement calculus. In this paper, we present a new reenement rule for loops that does not require a variant for termination, but uses a deadline command instead. To illustrate the calculus and the new loop introduction rule, we present an example reenement of a program that calculates the size of a kiwifruit from the time it takes to pass through a light beam.