Full Abstraction for Signal Flow Graphs

Signal flow graphs are classical structures in control theory, signal processing and a cornerstone in the study of feedback. Usually they are considered at an intuitive level and then translated into systems of linear equations. In this talk, we introduce the signal flow calculus, a formalism where signal flow graphs are first class objects. We introduce its graphical syntax (given in terms of string diagrams), a structural operational semantics (that make it similar to a process calculus) and a denotational semantics (in terms of subspaces of formal power series). We then relate the operational and the denotational semantics by a full abstraction result.