We give a list of canonical equivalence relations on discrete nets of the positive unit sphere of c0. This generalizes results of W. T. Gowers [1] and A. D. Taylor [5].

We define the A4-structure of a graph G to be the 4-uniform hypergraph on the vertex set of G whose edges are the vertex subsets inducing 2K2, C4, or P4. We show that perfection of a graph is determined by its A4-structure. We relate the A4structure to the canonical decomposition of a graph as defined by Tyshkevich [Discrete Mathematics 220 (2000) 201-238]; for example, a graph is indecomposabl...

This paper presents and philosophically assesses three types of results on the observational equivalence of continuous-time measure-theoretic deterministic and indeterministic descriptions. The first results establish observational equivalence to abstract mathematical descriptions. The second results are stronger because they show observational equivalence between deterministic and indeterminis...

This paper considers the real-valued random variables X1, . . . , Xn with corresponding distributions F1, . . . , Fn, such that X1, . . . , Xn admit some dependence structure and n(F1 + · · · + Fn) belongs to the class dominatedly varying-tailed distributions. The weak equivalence relations between the quantities P(Sn > x), P(max{X1, . . . , Xn} > x), P(max{S1, . . . , Sn} > x) and ∑n k=1 Fk(x)...

Subtyping in first order object calculi is studied with respect to the logical semantics obtained by identifying terms that satisfy the same set of predicates, as formalized through an assignment system. It is shown that equality in the full first order ς-calculus is modelled by this notion, which on turn is included in a Morris style contextual equivalence.

The concept of substantial equivalence, introduced for the risk assessment of genetically modified (GM) food, is a reducing concept because it ignores the context in which these products have been produced and brought to the consumer at the end of the food chain. Food quality cannot be restricted to mere substance and food acts on human beings not only at the level of nutrition but also through...

Techniques for reasoning about extensional properties of functional programs are well understood, but methods for analysing the underlying intensional or operational properties have been much neglected. This paper begins with the development of a simple but useful calculus for time analysis of non-strict functional programs with lazy lists. One limitation of this basic calculus is that the ordi...