Evolving Objects in Temporal Information Systems

This paper presents a semantic foundation of temporal conceptual models used to design temporal information systems. We consider a modelling language able to express both timestamping and evolution constraints. We conduct a deeper investigation of evolution constraints, eventually devising a model-theoretic semantics for a full-fledged model with both timestamping and evolution constraints. The proposed formalization is meant both to clarify the meaning of the various temporal constructors that appeared in the literature and to give a rigorous definition, in the context of temporal information systems, to notions like satisfiability, subsumption and logical implication. Furthermore, we show how to express temporal constraints using a subset of first-order temporal logic, i.e. DLRUS, the description logic DLR extended with the temporal operators Since and Until. We show how DLRUS is able to capture the various modelling constraints in a succinct way and to perform automated reasoning on temporal conceptual models

GIS Databases: From Multiscale to MultiRepresentation

Cartography is one of the major application areas using geographical databases. Whether it is for the business of producing paper maps for sale, or whether it is for displaying maps on a screen to visualize the result of a query, we need computer systems that know how to represent the same geographical area at different scales. The concept of multiscale database has become popular in the GIS domain as a way to enforce consistency between representations and reduce the global update load. Scaling, however, is just one of the facets that may lead to keeping several representations for the same real-world object. Viewpoint and classification are two major abstracttractions in the design process that also generate multiple representations. This paper investigates the generic issues and solutions to achieve flexible support of multiple representation in a GIS database

MurMur: A Research Agenda on MultipleRepresentations

One of the most publicized goals of modern computer society is to provide flexible access to information for everybody, anywhere, anytime. To make data management systems successful in satisfying user quest for information, an abstractolute requirement is the capability of tailoring the information to the peculiar needs of the targeted user. Unfortunately, this is a domain where current technology fails to support adequate functionality. Basically, existing approaches to such versatility rely on the idea that all possible views of a piece of information can be derived from a single ultimate representation. This may work in a centralized setting, but it is definitely unlikely to provide a sufficient framework in distributed, interoperable environments. This paper presents a research and development project that intends to explore the issue related to representation and management of multiple representations of the same reality. A specific focus of the project is spatio-temporal information and the support of multi-scale geographic databases, where objects are represented at many different resolution levels