A modal interface contract theory for guarded input/output automata with an application in traffic system design

As a direct contribution to recent efforts of bringing formal design-by-contract methods to hybrid systems, we introduce a variant of modal interface contract theory based on input/output automata with guarded transitions. We present an algebra of operators for interface composition, contract composition, contract conjunction, contract refinement and some theorems to demonstrate that our contract object has reasonably universal semantics. As an application, we use our framework to aid the design of a networked control system of traffic.