Continuity of operators on continuous and discrete time streams

Abstract

We consider the semantics of networks processing streams of data from a complete metric space. We consider two types of data streams: those based on continuous time (used in networks of physical components and analog devices), and those based on discrete time (used in concurrent algorithms). The networks are both governed by global clocks and together model a huge range of systems. Previously, we have investigated these two types of networks separately. Here we combine their study in a unified theory of stream transformers, given as fixed points of equations. We begin to develop this theory by using the standard mathematical techniques of topology to prove certain computationally desirable properties of these semantic functions, notably continuity, which is significant for models of a physical system, according to Hadamard’s principle.