. In this paper, we present two logics that allow for specifying distributed information systems, emphasizing communication among sites. The low-level logic D 0 offers features that are easy to implement but awkward to use for specification, while the high-level logic D 1 offers convenient specification features that are not easy to implement. We show that D 1 specifications may be automatically translated to D 0 in a sound and complete way. In order to prove soundness and completeness, we define our translation as a simple map of institutions. Our result may be useful for making implementation platforms like Corba easier accessible by providing high-level planning and specification methods for communication. 1 Introduction Two logics are presented that allow for specifying distributed information systems, emphasizing communication among sites. The low-level logic D 0 offers features that are easy to implement but awkward to use for specification, while the high-level logic D 1 offers...

A relaxed notion of category is presented having in mind the categorical caracterization of the mechanisms for combining probabilistic automata, since the composition of the appropriate morphisms is not always defined. A detailed discussion of the required notion of morphism is provided. The partiality of composition of such morphisms is illustrated at the abstract level of countable probability spaces. The relevant fragment of the theory of the proposed precategories is developed, including (constrained) products and Cartesian liftings. Precategories are precisely placed in the universe of neocategories. Some classical results from category theory are shown to carry over to precategories. Other results are shown not to hold in general. As an application, the precategorical universal constructs are used for characterizing the basic mechanisms for combining probabilistic automata: aggregation, interconnection and state constraining. Mathematics Subject Classifications: 18A10 68Q75. Ke...

Abstract. An important aspect of the feature interaction problem is to formally capture the notion of feature interactions. Although this notion is quite well informally understood by the researchers of the domain, the way, they handle it, strongly depends on the field of investigation they decide to work on (formal method application, architectural conception, technological research...). In this article, we focus on how formally specifying and studying feature systems, and both integration and interaction of features. More precisely, we aim to give a logic-independent framework to deal with the notions of feature, feature-based systems and feature interactions. Then, to help the reader's intuition, we instantiate it by a dynamic algebraic formalism and we give concrete examples of interactions between two features previously described in this formalism.

There is a growing interest in models for probabilistic systems. This fact is motivated by engineering applications, namely in problems concerning the evaluation of the performance of systems. It is of

Introduction The use of temporal logic has been widely explored both on the fields of specification and certification of properties of reactive systems (Pnueli, 1977), (Sernadas, 1980), (Fiadeiro and Maibaum, 1992), (Clarke, Grumberg and Kurshan, 1992), (Manna and Pnueli, 1992), (Manna and Pnueli, 1993), (Sernadas, Sernadas and Costa, 1995), (Sernadas, Sernadas and Ramos, 1996) and in monitoring (Hulsmann and Saake, 1991), (Kung, 1984), (Lipeck and Saake, 1987), (Schwiderski, Hartmann and Saake, 1994). The advantages are known to lie on the clear declarative formalization of the system at hand and on the use of temporal verification techniques to prove properties of the specified systems. Temporal logic specification has also given an important contribution towards the establishment of suitable compositional specification frameworks (Barringer, Kuiper and Pnueli, 1984). -- This work was partly supported by CEC under ESPRIT-III BRA WG 6071 IS-CORE (Information S

The temporal logic institution