Abstract not found

This paper axiomatises the structure of bigraphs, and proves that the resulting theory is complete. Bigraphs are graphs with double structure, representing locality and connectivity. They have been shown to represent dynamic theories for the #-calculus, mobile ambients and Petri nets, in a way that is faithful to each of those models of discrete behaviour. While the main purpose of bigraphs is to understand mobile systems, a prerequisite for this understanding is a well-behaved theory of the structure of states in such systems. The algebra of bigraph structure is surprisingly simple, as the paper demonstrates; this is because bigraphs treat locality and connectivity orthogonally

this paper involve sentences with the verb "be.""Be" and other state verbs comprise a complicated and interesting class. Ttley accept a lot of different constructions (adjectival predicates, nominal predicates. prepositional phrase complements, etc.), and provide a convenient and convincing field for preliminary investigations. At the same time, much of the work done for state verbs (cordiuation, PP relationships, etc.) can be applied to other verb classes

Bigraphs are emerging as a (meta-)model for concurrent calculi, like CCS, ambients, πcalculus, and Petri nets. They are built orthogonally on two structures: a hierarchical place graph for locations and a link (hyper-)graph for connections. Aiming at describing bigraphical structures, we introduce a general framework, BiLog, whose formulae describe arrows in monoidal categories. We then instantiate the framework to bigraphical structures and we obtain a logic that is a natural composition of a place graph logic and a link graph logic. We explore the concepts of separation and sharing in these logics and we prove that they generalise well known spatial logics for trees, graphs and tree contexts. As an application, we show how XML data with links and web services can be modelled by bigraphs and described by BiLog. The framework can be extended by introducing dynamics in the model and a standard temporal modality in the logic. However, in some cases, temporal modalities can be already expressed in the static framework. To testify this, we show how to encode a minimal spatial logic for CCS in an instance of BiLog.

This series consists of papers intended to stimulate discussion. Some of the papers are of a preliminary character and should thus not be referred to or quoted without permission from the author(s). The interpretations and conclusions in this paper are those of the author(s) and do not necessarily represent the views of the Department of Economics and Social Sciences nor of the Agricultural University of Norway. iiStrengths and weaknesses of the co-operative form; A matter of perspectiv and opinion This paper focuses on the dramatic changes going on in most co-operative organised business entities in the western world, their transition and conversion into public companies or public company like structures. The perspective and main issue is the competitiveness of the co-operative organisational form. The question is not the trade off between democracy and social responsibility on the one side, and business efficiency on the other. It is rather: What is the