We check that there exists a structure of model category on the category of flows whose weak equivalences are the S-homotopy equivalences. This model structure is simplicial, but not topological.

A significant problem with current diagnostic test generation techniques is the time spent in identifying diagnostic equivalences amongst fault pairs. Fault pair distance analysis is introduced in this paper to characterize diagnostically equivalent fault pairs and motivate local circuit transformations and structural analysis to identify equivalences in combinational circuits rapidly. Our resu...

The efficiency of regular expression matching algorithms depends very much on the size of the nondeterministic finite automata (NFA) obtained from regular expressions. Reducing the size of these automata by using equivalences has been shown to reduce significantly the search time. We consider the problem of reducing the size of arbitrary NFAs using equivalences and preorders. For equivalences, ...

In this paper, we explore the structure of the set of all regular equivalences (White and Reitz 1983) proving that it forms a lattice, and suggest a general approach to computing certain elements of the lattice. The resulting algorithm represents a useful complement to the White and Reitz algorithm, which can only find the maximal regular equivalence of a graph. Using this algorithm, it is poss...

We introduce a general categorical framework for the definition of weak behavioural equivalences, building on and extending recent results in the field. This framework is based on special order enriched categories, i.e. categories whose homsets are endowed with suitable complete orders. Using this structure we provide an abstract notion of saturation, which allows us to define various (weak) be...

This paper investigates Bio-PEPA, the stochastic process algebra for biological modelling developed by Ciocchetta and Hillston. It focusses on Bio-PEPA with levels where molecular counts are grouped or concentrations are discretised into a finite number of levels. Basic properties of well-defined Bio-PEPA systems are established after which equivalences used for the stochastic process algebra P...

In the field of Security, process equivalences have been used to characterize various information-hiding properties (for instance secrecy, anonymity and non-interference) based on the principle that a protocol P with a variable x satisfies such property if and only if, for every pair of secrets s1 and s2, P [1/x] is equivalent to P [2/x]. We argue that, in the presence of nondeterminism, the ab...

This paper investigates the optimisation of aggregation functions in the context of computationally complete database programming languages and aims to generalise and provide a unifying formal foundation for previous work. We deene a `fold' operator over collection types in terms of which operations such as selection, projection, join and group-by can be deened, as well as aggregation functions...

Behavioural equivalences of labelled transition systems are characterized in terms of homomorphic transformations. This permits relying on algebraic techniques for proving systems properties and reduces equivalence checking of two systems to studying the relationships among the elements of their structures. Di6erent algebraic characterizations of bisimulation-based equivalences in terms of part...