8618172
Tentative steps toward a development method for interfering programs
Development methods for (sequential) programs that run in isolation have been studied elsewhere. Programs that run in parallel can interfere with each other, either via shared storage or by sending messages. Extensions to earlier development methods are proposed for the rigorous development of interfering programs. In particular, extensions to the specification method based on postconditions that are predicates of two states and the development methods of operation decomposition and data refinement are proposed. 41 references.
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.
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.
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.
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.
11309996
Automated methods of predicting the function of biological sequences using GO and BLAST
BackgroundWith the exponential increase in genomic sequence data there is a need to develop automated approaches to deducing the biological functions of novel sequences with high accuracy. Our aim is to demonstrate how accuracy benchmarking can be used in a decision-making process evaluating competing designs of biological function predictors. We utilise the Gene Ontology, GO, a directed acyclic graph of functional terms, to annotate sequences with functional information describing their biological context. Initially we examine the effect on accuracy scores of increasing the allowed distance between predicted and a test set of curator assigned terms. Next we evaluate several annotator methods using accuracy benchmarking. Given an unannotated sequence we use the Basic Local Alignment Search Tool, BLAST, to find similar sequences that have already been assigned GO terms by curators. A number of methods were developed that utilise terms associated with the best five matching sequences. These methods were compared against a benchmark method of simply using terms associated with the best BLAST-matched sequence (best BLAST approach).ResultsThe precision and recall of estimates increases rapidly as the amount of distance permitted between a predicted term and a correct term assignment increases. Accuracy benchmarking allows a comparison of annotation methods. A covering graph approach performs poorly, except where the term assignment rate is high. A term distance concordance approach has a similar accuracy to the best BLAST approach, demonstrating lower precision but higher recall. However, a discriminant function method has higher precision and recall than the best BLAST approach and other methods shown here.ConclusionAllowing term predictions to be counted correct if closely related to a correct term decreases the reliability of the accuracy score. As such we recommend using accuracy measures that require exact matching of predicted terms with curator assigned terms. Furthermore, we conclude that competing designs of BLAST-based GO term annotators can be effectively compared using an accuracy benchmarking approach. The most accurate annotation method was developed using data mining techniques. As such we recommend that designers of term annotators utilise accuracy benchmarking and data mining to ensure newly developed annotators are of high quality.
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.
7423994
Computational Perspectives on Map Generalization
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
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.