Keith T. Mason

A formal approach to imperfection in geographic information

Traditional computational models of geographic phenomena offer no room for imperfection. Underlying this tradition is the simplifying assumption that reality is certain, crisp, unambiguous, independent of context, and capable of quantitative representation. This paper reports on initial work which explicitly recognises that most geographic information is intrinsically imperfect. Based on an ontology of imperfection the paper explores a formal model of imperfect geographic information using multi-valued logic. The development of Java software able to assist with a geodemographic retail site assessment application is used to illustrate the utility of a formal approach.

Qualitative reasoning about consistency in geographic information

This paper explores the development and use of a qualitative reasoning system for describing consistency between different geographic data sets. Consistency is closely related to issues of uncertainty and interoperability in geographic information, and the paper assesses how automated reasoning about consistency can be used to support the integration of heterogeneous geographic data sets. The system developed is based on description logic. The decidability and tractability characteristics of description logic allow consistency checking to be deferred during data integration, so minimizing the information loss that usually accompanies any data integration task. Further, the user interface allows users to negotiate with the system in defining consistency. The results of the research suggest that further work could significantly increase the level of automation for many geographic data integration tasks.

Tripod: a comprehensive system for the management of spatial and aspatial historical objects

Spatio-temporal databases have been the focus of considerable research attention in recent years. To date, much of this work has focused on the relational data model, with object data models receiving far less consideration. Where descriptions of such object models do exist, there is currently a lack of systems that build upon these models to produce database architectures that address the broad spectrum of issues related to the delivery for a fully fuctional spatio-temporal DBMS. This paper presents an overview of such a system by describing a spatio-historical object DBMS that utilises a specialised mechanism, called a history, for maintaining knowledge about entities that change over time. Key features of the resulting proposal include: (i) consistent representations of primitive spatial and temporal types; (ii) a component-based design in which spatial, temporal and historical extensions are formalised incrementally, for subsequent use together or separately; (iii) compatibility with mainstream query processing frameworks for object databases; and (iv) the integration of the spatio-temporal proposal with the ODMG standard.

Tripod: A Comprehensive Model for Spatial and Aspatial Historical Objects

Spatio-temporal extensions to data models have been an active area of research for a number of years. To date, much of this work has focused on the relational data model, with object data models receiving far less consideration. This paper presents a spatio-historical object model that uses a specialized mechanism, called a history, to maintain knowledge about entities that change over time. Key features of the resulting proposal include: (i) consistent representations of primitive spatial and temporal types; (ii) a component-based design in which spatial, temporal and historical extensions are formalized incrementally, for subsequent use together or separately; (iii) a formally specified data model. The model can be used directly during the design of spatio-historical applications, but also forms the basis of an implementation activity developing a spatio-historical object database management system.

Trauma systems and major injury centres for the 21st century: an option.

Trauma, especially involving accidents and falls is now the leading cause of death in the UK in the first four decades of life. This paper looks at the existing pattern of Accident and Emergency Units and suggests that because it has grown up in a fragmented and poorly co-ordinated fashion and because it is subjected to demands that it was not designed for, it is inadequate in dealing with the most severe injury cases. Following collaborative work with researchers at the North Staffordshire Hospital, the authors propose a system of thirty major trauma centres to cover the whole of the UK. Each would deal with the most severe accident cases from surrounding hospitals. Using data from the census and from health authorities, analysed within a GIS environment, a locational pattern for these centres is suggested and their catchment areas are outlined.

Tripod: A Spatio-Historical Object Database System

The storage and analysis of large amounts of time varying spatial and aspatial data is becoming an important feature of many application domains. This requirement has fueled the need for spatio-temporal extensions to data models and their associated querying facilities. To date, much of this work has focused on the relational data model, with object data models receiving far less consideration. Where descriptions of such object models do exist, there is currently a lack of systems which build upon these models to produce database architectures that address the broad spectrum of issues related to the delivery of a fully functional spatio-temporal DBMS. This chapter presents an overview of such a system by describing a spatio-historical object model that utilizes a specialized mechanism, called a history, for maintaining knowledge about entities that change over time, and a tour through the query processing architecture of the system. Key features of the resulting proposal include: (i) consistent representations of primitive spatial and timestamp types; (ii) a component-based design in which spatial, timestamp and historical extensions are formalized incrementally, for subsequent use together or separately; (iii) compatibility with mainstream query processing frameworks for object databases; and (iv) the integration of the spatio-temporal proposal with the ODMG standard.

Spatio-temporal databases in practice: directly supporting previously developed land data using tripod

This article presents a complete spatio-temporal object DBMS called Tripod, in the context of an application to support the management of previously developed land (PDL). In particular the article focuses on: the techniques that are available to realise the application data model; the facilities necessary to realise the operational semantics of updates, and the facilities that are available to identify interesting patterns of spatio-temporal change. Whilst there exist other proposals for data models and query languages for spatio-temporal object databases, Tripod is unique in that it provides: a complete implementation of an expressive spatio-temporal data model to allow modelling of (a)spatial time-varying data; the first example of an implementation of language bindings to support manipulation of stored data; and the first complete implementation of a spatio-temporal OQL that we know of. The article also focuses on the benefits arising from use of a spatio-temporal DBMS on an important category of application, namely land parcel management.