We discuss session types independently of any programming language. We then embody the notion in languages from three different paradigms: the pi calculus, a functional language, and an object-oriented language.

We review links between three logic formalisms and three approaches to specifying operational semantics. In particular, we show that specifications written with (small-step and big-step) SOS, abstract machines, and multiset rewriting, are closely related to Horn clauses, binary clauses, and (a subset of) linear logic, respectively. We shall illustrate how binary clauses form a bridge between th...

The analysis of large-scale software is difficult in the absence of supporting tools, due to the sheer size and complexity of today’s systems. We present CODECITY, a language-independent interactive 3D visualization tool for the analysis of large object-oriented software systems. Using a city metaphor, it depicts classes as buildings and packages as districts of a “software city”. We start pres...

This is an extended version of an essay with the same title that I wrote for the workshop Algebraic Process Calculi: The First Twenty Five Years and Beyond, held in Bertinoro, Italy in the first week of August 2005.

In the k-set agreement problem, each process proposes a value and has to decide a value in such a way that a decided value is a proposed value and at most k different values are decided. This problem can easily be solved in synchronous systems or in asynchronous systems prone to t process crashes when t < k. In contrast, it has been shown that k-set agreement cannot be solved in asynchronous sy...

Bacterial cell-to-cell communication (‘quorum sensing’) is mediated by structurally diverse, small diffusible signal molecules which regulate gene expression as a function of cell population density. Many different Gramnegative animal, plant and fish pathogens employ Nacylhomoserine lactones (AHLs) as quorum sensing signal molecules which control diverse physiological processes including biolum...