General Refinement, Part One: Interfaces, Determinism and Special Refinement

We introduce a general model of refinement. This is defined in terms of what contexts an entity can appear in, and what observations can be made of it in those contexts. We show explicitly how five refinement relations, taken from the refinement literature, are instances of our general model. Henceforth, since they are specialisations of a general model, we call these instances special models. We show these theories of refinement are special models simply by fixing the sets of contexts and observations involved in appropriate ways.