Capturing the dynamism of situation in the flow of information

This paper begins by considering requirements for verification tools for NextGen, the US National Airspace System under development. Category theory and channel are reviewed as well as their contribution to computer science, and how these theories can be useful in the development of NextGen is outlined. Category theory is a branch of mathematics that can provide a unified presentation of much of abstract mathematics, and channel theory uses concepts from category theory to provide an abstract and rigorous account of how information about some system component can carry information about other components. The second half of this paper introduces a notion of change into channel theory, which involves augmenting channel theory with situation theory. A "change" relation is defined on the basic units of information ("infons"), which induces a topological space on situations. The topology supports a notion of information updated as time progresses but receding as we project into the future.