We introduce a concise pi-calculus with directed choices and develop a theory of subtyping. Built on a simple behavioural intuition, the calculus offers exact semantic analysis of the extant notions of subtyping in functional programming languages and session-based programming languages. After illustrating the idea of subtyping through examples, we show type-directed embeddings of two known sub...

OBJECTIVES Antibiotic resistance among Escherichia coli is globally an increasing problem in public healthcare. Understanding the spread of plasmid-mediated ESBL genes is of great importance in elucidating their molecular epidemiology. However, differentiation of subtypes and alleles is frequently hampered by the lack of comprehensive diagnostic tools. We therefore developed a novel universal b...

Session types allow high-level specifications of structured patterns of communication, such as client-server protocols, to be expressed as types and verified by static typechecking. In collaboration with Malcolm Hole, we have previously introduced a notion of subtyping for session types, formulated for an extended pi calculus. Subtyping allows one part of a system, for example a server, to be r...

Salmonellosis is one of the most common causes of foodborne infection and a leading cause of human gastroenteritis. Throughout the last decade, Salmonella enterica serotype Typhimurium (ST) has shown an increase report with the simultaneous emergence of multidrug-resistant isolates, as phage type DT104. Therefore, to successfully control this microorganism, it is important to attribute salmonel...

Category theory has been used extensively and successfully in modeling functional programming languages (see, e.g., [22, 23, 17, 20, 25, 15]). However, it has been used to a lesser extent in understanding and modeling object-oriented programming (OOP) languages, mainly focusing on OO languages extant during the early days of OOP research [13, 16, 18, 21]. Recently, we presented a detailed outli...

We compare Meyer and Routley’s minimal relevant logic B+ with the recent semanticsbased approach to subtyping introduced by Frisch, Castagna and Benzaken in the definition of a type system with intersection and union. We show that – for the functional core of the system – such notion of subtyping, which is defined in purely set-theoretical terms, coincides with the relevant entailment of the lo...

A cholera outbreak in Laos in July 2010 involved 237 cases, including 4 deaths. Molecular subtyping indicated relatedness between the Vibrio cholerae isolates in this and in a 2007 outbreak, uncovering a clonal group of V. cholerae circulating in the Mekong basin. Our finding suggests the subtyping methods will affect this relatedness.

This paper studies the question of when one abstract data type (ADT) is a behavioral subtype of another, and proposes a model-theoretic notion of weak behavioral subtyping. Weak behavioral subtyping permits supertype abstraction to be a sound and modular reasoning principle in a language with mutation and limited forms of aliasing. The necessary restrictions on aliasing can be statically checked.

Subtyping is an important concept and used in many programming languages. One approach to give semantics to languages with subtypes is by translation to target languages without subtyping: Subtypings A ≤ B are interpreted via conversion functions A → B. This paper shows how to extend the method to languages with computational effects, using Moggi’s computational metalanguage.

I review the Liskov and Wing subtype deenition that takes into consideration the problem of subtyping in the presence of mutable objects. I then show how this notion of subtyping is relevant to the design of the TOM object repository whose main application today is a data type conversion service accesssible through the Web.