Algebraic properties specify some natural properties of programming and specification constructs. This paper provides an overview of techniques to guarantee or generate algebraic properties of language constructs by investigating the syntactic shape of the deduction rules defining their operational semantics.

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...