204995524
A Run-Time Mechanism for Referencing Variables
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.
2399941
Operational semantics: Concepts and their expression
38308402
Specification and Design of (Parallel) Programs
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.
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.
7423994
Computational Perspectives on Map Generalization
13190855
Conflict resolution in cartographic name placement
Abstract The increasing application of computer cartography in geographical information systems and in professional map production has highlighted the requirement for automatic positioning of cartographic text in a manner that ensures legibility. An important aspect of the implementation of automated name placement is the avoidance of conflict, in particular due to overlap between names, and between names and map features. This paper reviews the automated strategies that have been adopted for conflict resolution. The majority of these may be classified as either iterative or graph-search procedures. In general the problem may be seen as one in which initially trial positions are generated for each of a selected set of names. These trial positions should obey rules relating to text characteristics and to the relationships between names and other map features. Conflict resolution then consists in finding, for each name, a trial position that obeys the cartographic rules governing the relationships between names.
42189866
Episodes in Space: Qualitative Representation and Reasoning Over Spatio-Temporal Objects
There is growing interest in many application domains for the temporal treatment and manipulation of spatially referenced objects. Handling the time dimension in spatial databases can greatly enhance and extend their functionality and usability by offering means of understanding the spatial behaviour in time. Few works, to date, have been directed towards the development of formalisms for representation and reasoning in this domain. In this paper, a new approach is presented for the representation and reasoning over spatio-temporal relationships. The approach is simple and aims to satisfy the requirements of coherency, expressiveness and reasoning power. Consistent behaviours of spatial objects in time are denoted episodes. The topology of the domain is defined by decomposing episodes into representative components and relationships are defined between those components. Spatio-temporal reasoning is achieved by composing the relationships between the object components using constraint networks. New composition tables between simple spatio-temporal regions and between regions and volumes are also derived and used in the reasoning process.
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. >
6465500
Proximity Search with a Triangulated Spatial Model
The proximity relations inherent in triangulations of geometric data can be exploited in the implementation of nearest-neighbour search procedures. This is relevant to applications such as terrain analysis, cartography and robotics, in which triangulations may be used to model the spatial data. Here we describe neighbourhood search procedures within constrained Delaunay triangulations of the vertices of linear objects, for the queries of nearest object to an object and the nearest object to an arbitrary point. The procedures search locally from object edges, or from a query point, to build triangulated regions that extend from the source edge or point by a distance at least equal to that to its nearest neighbouring feature. Several geographical datasets have been used to evaluate the procedures experimentally. Average numbers of edge‐edge distance calculations to find the nearest line feature edge disjoint to another line feature edge ranged between 15 and 39 for the different datasets examined, while the average numbers of point‐edge distance calculations to determine the nearest edge to an arbitrary point ranged between 7 and 35.