For a finite lattice L, the congruence lattice ConL of L can be easily computed from the partially ordered set J(L) of join-irreducible elements of L and the join-dependency relation DL on J(L). We establish a similar version of this result for the dimension monoid DimL of L, a natural precursor of ConL. For L join-semidistributive, this result takes the following form: Theorem 1. Let L be a fi...

For a finite lattice L, let EL denote the reflexive and transitive closure of the join-dependency relation on L, defined on the set J(L) of all join-irreducible elements of L. We characterize the relations of the form EL, as follows: Theorem. Let E be a quasi-ordering on a finite set P . Then the following conditions are equivalent: (i) There exists a finite lattice L such that 〈J(L),EL〉 is iso...

Using group actions and generating functions, we derive various arithmetic properties of the q-binomial coefficients and q-Stirling numbers. These include recurrence relations and computation of residues modulo a cyclotomic polynomial. We also obtain periodicity and non-periodicity results. 0 IWZ Academic PIS, II-S.

The Algebra of Connectors AC(P ) is used to model structured interactions in the BIP component framework. Its terms are connectors, relations describing synchronization constraints between the ports of component-based systems. Connectors are structured combinations of two basic synchronization protocols between ports: rendezvous and broadcast. In a previous paper, we have studied interaction se...

Abs t rac t . Action refinement in process algebras has been widely studied in the last few years as a means to support top-down design of systems. A specific notion of refinement arises when a dependency relation on the actions (in the Mazurkiewicz sense) is used to control the inheritance of orderings from the abstract level. In this paper we present a rather simple operational semantics for ...

Legg-Calvé-Perthes disease (LCPD) is an idiopathic osteonecrosis of the femoral head with variable complications and resultant deformity of the femoral head and osteoarthritis. Suggested risk factors are acetabular retroversion, obesity, latitude, hyperactivity, and coagulopathy. The most commonly applied classification is based on radiolucency in the lateral pillar of the femoral head, which i...

We propose a theory of process re nement which relates behavioural descriptions belonging to conceptually di erent abstraction levels through a so called vertical implementation relation The theory is based on action re nement which permits to relate abstract actions of the speci cation to concrete computations of the implementation it is developed in the standard interleaving approach A number...

This paper presents congruence results of a behavioural equivalence on a graph rewriting model of concurrent pro cesses with higher-order communication. A bipartite di rected acyclic graph represents a concurrent system that consists of a number of processes and messages in our model. The model presented here makes it possible to repre sent local names that their scopes are not nested. We show ...

We propose a theory of process reenement which relates behavioural descriptions belonging to conceptually diierent abstraction levels, through a so-called vertical implementation relation. The theory is based on action reenement, which permits to relate abstract actions of the speciication to concrete computations of the implementation; it is developed in the standard interleaving approach. A n...

We present a logical theory of space where only tridimensional regions are assumed in the domain. Three distinct primitives are used to describe their mereological, topological and morphological properties: mereology is described by a parthood relation satisfying the axioms of Closed Extensional Mereology; topology is described by means of a "simple region" predicate, by which a relation of “st...