We extend the framework of Pure Type Systems with sub-typing, as found in F !. This leads to a concise description of many existing systems with subtyping, and also to some new interesting systems. We develop the meta-theory for this framework, including Subject Reduction and Minimal Typing. The main problem was how to formulate the rules of the framework in such a way that we avoid circulariti...

We generalise a theory of multiparty session types for the π-calculus through asynchronous communication subtyping, which allows partial commutativity of actions with maximal flexibility and safe optimisation in message choreography. A sound and complete algorithm for the subtyping relation, which can calculate conformance of optimised end-point processes to an agreed global specification, is p...

Verification of a dynamically-dispatched method call, E .m(), seems to depend on E ’s dynamic type. To avoid case analysis and allow incremental development, object-oriented program verification uses supertype abstraction. That is, one reasons about E .m() using m’s specification for E ’s static type. Supertype abstraction is valid when each subtype in the program is a behavioral subtype. This ...

Subtyping is a crucial ingredient of session type theory and its applications, notably to programming language implementations. In this paper, we study effective ways to check whether a session type is a subtype of another by applying a characteristic formulae approach to the problem. Our core contribution is an algorithm to generate a modal μ-calculus formula that characterises all the superty...

Semantic subtyping between coinductive record types supports accurate type analysis of object-oriented languages, by introducing Boolean type constructors and modeling cyclic objects. In previous work, a sound and complete algorithm for semantic subtyping has been proposed, but only for coinductive immutable record types with unions. In this work we address the issue of extending the previous r...

The object-oriented paradigm is increasingly used in the implementation and the use of web services. However, the mismatch between objects and document structures in the wire has a negative impact over interoperability, more particularly when subtyping is involved. In this paper, we discuss how to improve interoperability in this context by preserving the subsumption property associated to subt...

Behavioural typing and subtyping has proved to be a very useful concept for the support of incremental reuse in the area of object-oriented (O-O) languages. With the emergence of formalisms integrating the O-O approach and Petri nets, the question arises how behavioural subtyping may be supported by such formalisms. We present a formal framework for the definition of behavioural typing in CoOpe...

In sequential classand mixin-based settings, subtyping is essentially a relation on objects: no subtype relation is defined on classes and mixins, otherwise there would be conflicts with the inheritance mechanism, creating type un-safety. Nevertheless, a width-depth subtyping relation on class and mixin types is useful in the realm of mobile and distributed processes, where object-oriented code...

In information systems modeling, the business domain being modeled often exhibits subtyping aspects that can prove challenging to implement in either relational databases or object-oriented code. In practice, some of these aspects are often handled incorrectly. This paper examines a number of subtyping issues that require special attention (e.g. derivation options, subtype rigidity, subtype mig...

avian influenza virus (aiv) infection is a major cause of bird or human mortality and morbidity, therefore the rapid identification of the virus is of important clinical and epidemiological implication. methods: a multiplex reverse transcriptase pcr (rt-pcr) was optimized for the detection of influenza a virus and the h5 and h9 subtypes. the influenza type a specific primers were directed to th...