6772552
Fixing the semantics of some concurrent object-oriented concepts
Abstract Concurrent object-oriented languages provide a suitable target for a compositional design process that copes with the interference inherent with concurrency. Fixing the semantics of an object-based design language has been undertaken using structured operational semantics and by a mapping to the pi-calculus. These two approaches are outlined and contrasted. In particular, the difficulties in the two approaches of justifying the proof rules of the proposed design method are explained.
38308402
Specification and Design of (Parallel) Programs
9236653
The Early Search for Tractable Ways of Reasoning about Programs
This article traces the history - up to around 1990 - of research on reasoning about programs. The main focus is on sequential imperative programs but some comments are made on concurrency. The main thesis is that the idea of reasoning about programs has been around since they were first written; the search has been to find tractable methods.
2399941
Operational semantics: Concepts and their expression
28161210
Modularizing the Formal Description of a Database System
Specification languages have been proposed, and are being developed, which offer ways of splitting specifications into separate components or modules. It is important that such languages are able to cope with modularizations which are required by realistic specification tasks. This paper offers a challenge problem in modularization based on a description is of an existing database system. The chosen modularization is motivated by the need to separate coherent units about which useful properties can be deduced.
15308825
Scientific Decisions which Characterize VDM
The formal description and development method known as VDM has been used extensively, its specification language is now an ISO standard, and it has influenced other specification languages. The origins of VDM are normally placed in language description or semantics but it is probably best known in the wider arena of formal methods for (general) program specification and design. This paper sets out a personal view of some of the key technical decisions which characterize the Vienna Development Method.
6251055
End-User Programming
End-user software development is a growing avocation in every industry and every country. By the middle of the next century, computer literacy and programming skills will be almost as common as reading and writing skills. Almost every knowledge worker in the world will be able to program if he or she sets out to do so. The implications of widespread end-user software are only just beginning to be considered. There are many exciting possibilities and some potential hazards. The time is now at hand to consider business topics such as ownership of end-user applications and liability in cases of significant errors. >
31900993
Geographical Interfaces to Museum Collections
14219539
Characterisation and generalisation of cartographic lines using Delaunay triangulation
A method is presented for generalising cartographic lines using an approach based on determination of their structure. Constrained Delaunay triangulation is used to construct a skeleton of the space surrounding the lines and hence represent line features in terms of skeleton branches. Several statistical measures are used to characterise the triangulation branches. The measures enable selective generalisation of different types of line feature, leading to the possibility of user-specification of the style of generalisation. In our implementation of the approach, the triangulation is updated dynamically to allow both sides of multiple lines to be processed, while guaranteeing topological consistency between the resulting generalised lines.
36993113
A Collaborative Schema Integration System
Conceptual modelling as applied to database development can be described as a two stage process: schema modelling followed by schema integration. Schema modelling is the process of transforming individual user requirements into a conceptual schema: an implementation-independent map of data requirements. Schema integration is the process of combining individual conceptual schemas into a single, unified schema. Single-user tools for schema modelling have enjoyed much success partly because the process of schema modelling has become relatively well formalised. Although a number of formal approaches to conducting schema integration have been proposed, it appears that schema integration tools have not enjoyed the same level of success. This we attribute not so much to the problem of formalisation but to the inherent collaborative nature of schema integration work. This paper first discusses the importance of collaboration to schema integration work. It then describes SISIBIS, a demonstrator system employing the IBIS (Issue Based Information System) scheme to support collaborative database design.
33896540
A Triangulated Spatial Model for Cartographic Generalisation of Areal Objects
Cartographic generalisation involves interaction between individual operators concerned with processes such as object elimination, detail reductions amalgamation, typification and displacement. Effective automation of these processes requires a means of maintaining knowledge of the spatial relationships between map objects in order to ensure that constraints of topology and of proximity are obeyed in the course of the individual generalisation transformations. Triangulated spatial models, based on the constrained Delaunay triangulation, have proven to be of particular value in representing the proximal and topological relations between map objects and hence in performing many of the essential tasks of fully automated cartographic generalisation. These include the identification of nearby objects; determination of the structure of space between nearby objects; execution of boundary simplification, merge and collapse operations; and the detection and resolution, by displacement, of topological inconsistencies arising from individual operators. In this paper we focus on the use of a triangulated model for operations specific to execution of merge operations between areal objects. The model is exploited to identify the regions of space between nearby objects and to execute merge operations in which the triangulation is used variously to adopt intervening space and to move adjacent rectangular objects to touch each other. Methods for updating the triangulation are described.