16447462
Accommodating interference in the formal design of concurrent object-based programs
This paper is about formal development methods for concurrent programs. Interference is the bane of the quest for compositional methods for concurrency. Concepts from object-oriented languages are argued to be a promising way of taming interference. Two approaches to development are described which are applicable to differing degrees of interference.
2399941
Operational semantics: Concepts and their expression
45828501
Formal Definition in Program Development
The intent of the current paper is to show how a large problem like compiler development can be divided in a way which provides a structure for arguments of correctness. Although mechanically checked proofs are not envisaged, the use of formal notation is recommended so that the basis for correctness arguments exists.
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.
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.
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.
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.
12540236
Map generalization in the Web age
Geographic information represents our understanding of the association of phenomena with their location on and near the Earth’s surface. When presented in map form, an essential aspect of that information is that it may be adapted in semantic abstraction and level of geometric detail according to the purpose of the map and the extent of the Earth that is being considered at any one time. Representations of small areas in detail result in so-called large-scale maps, while representations of large regions in lesser detail are referred to as small-scale maps. Traditionally, cartographers have performed the task of adapting the content and the level of detail of a map to suit its scale and purpose, and this process is called map generalization. The widespread use of geographic information in computers in the context of geographical information systems (GIS) has brought with it the demand for automation of map generalization. Ideally, when accessing geographic information in a GIS, it would be possible to be able to modify the level of generalization of the available geo-data entirely automatically. At present, no such automatic facilities are readily available in commercial GIS. Some commercial GIS do provide mapgeneralization tools that the user may apply in a somewhat ad hoc manner to selected geometric data. These tools appear, however, to be targeted at cartographic specialists wanting to derive a generalized dataset from a more detailed one. There are some notable examples of the way in which automated map-generalization tools have been exploited for purposes of professional map production. For example, the Institut Géographique National of France have used GALBE (this issue) to generalize the entire French road network to produce 1 : 250 000 scale maps from their BDCarto database (approximately 1 :50 000). More recently, the demand for automated map generalization, which has been longstanding in the context of conventional GIS, has been reinforced by the prevalence of geographical information access on the Internet. There are several types of public access map-based Web sites that allow a user to zoom in and out of a particular region, but at present this is usually based on stepping between independent pre-generalized datasets which may differ markedly in their degree of generalization. It would be desirable to be able to change the level of detail on such systems in a smooth and progressive manner rather than the quantum-leap changes that often characterize the current approach. Hand-held computers and mobile phones with small screens can now support the display of small maps, but the size
26658779
Virtual architecture based on a binary relational model: A museum hypermedia application
205571678
A Prolog Rule-Based System for Cartographic Name Placement
Manual name placement is an extremely time consuming task and has been one of the most difficult aspects of the map production process to automate. It is complicated by the large number of rules required for the selection and placement of names. A hybrid Prolog/Fortrau rule-based system is described for placing names on a variety of map types. It uses a set of Prolog primitives for spatial search and name placement operations. The Ordnance Survey's 1:625000 scale digital dataset has been used to illustrate the application of rules for the selection of labels as well as for controlling their size and orientation. The application to other types of maps and diagrams is also briefly described.
6079094
Haptic interface control-design issues and experiments with a planar device
Describes the haptic rendering of a virtual environment by drawing upon concepts developed in the area of teleoperation. A four-channel teleoperation architecture is shown to be an effective means of coordinating the control of a 3-DOF haptic interface with the simulation of a virtual dynamic environment.