Colombeau algebras on a C∞-manifold

In this paper Colombeau's algebra of functions on Rn, containing the distributions, is generalized to a sheaf on a C∞-manifold. The well-known problem of restricting distributions to a submanifold is solved within this framework

Swifterbant S4 (the Netherlands):Occupation and exploitation of a Neolithic levee site (c. 4300-4000 cal. BC)

This publication presents the results of the 2005-2007 excavations at Swifterbant S4, carried out by the Groningen INstitute of Archaeology. S4 is a well-preserved Neolthic wetland site (c. 4300-4000 cal. BC) located within the Swifterbant river system in the Netherlands. We present the landscape setting, the various find categories and the spatial patterns with three research themes in mind. Theme 1 concerns the environmental setting, subsistence and site function. We conclude that the Swifterbant hunter-gatherer-farmers exploited a mosaic-type landscape. Theme 2 deals with developments in site function during the exploitation and exploitation history of the site. This analysis leads to the observation that episodes of cultivation and settlement alternated at S4. Theme 3, the use of space, was difficult to study due to the fragmented nature of the excavation plan. This site monograph makes Swifterbant S4 the most comprehensively published site of the Swifterbant river system

Composition mechanisms for retrenchment

Retrenchment is a flexible model evolution formalism that arose as a reaction to the limitations imposed by refinement, and for which the proof obligations feature additional predicates for accommodating design data. Composition mechanisms for retrenchment are studied. Vertical, horizontal, dataflow, parallel and fusion compositions are described. Of particular note are the means by which the additional predicates compose. It is argued that all of the compositions introduced are associative, and that they are mutually coherent. Composition of retrenchment with refinement, so important for the smooth interworking of the two techniques, is discussed. Decomposition, allowing finer grained retrenchments to be extracted from a single large grained retrenchment, is also investigated

Extending the theory of Owicki and Gries with a logic of progress

This paper describes a logic of progress for concurrent programs. The logic is based on that of UNITY, molded to fit a sequential programming model. Integration of the two is achieved by using auxiliary variables in a systematic way that incorporates program counters into the program text. The rules for progress in UNITY are then modified to suit this new system. This modification is however subtle enough to allow the theory of Owicki and Gries to be used without change