1,721,021 research outputs found
Towards Declarative GIS Analysis
No full textThe paper proposes an integration between GIS technology and deductive databases technology. The integration provides the user with a declarative language to support GIS analysis. The language is based on a well established theory of logic program algebras developed by the authors in recent years as an extension of deductive databases. An example of application is provided to show the benefits of the approach. Extensions to manage multiple, heterogeneous GIS, and issues for making the approach more practical are addressed
Qualitative reasoning with a Spatio-Temporal language
No full textIn this paper we present an approach to qualitative spatial reasoning based on the spatio-temporal language STACLP 18. In particular, we show how the topological 9-intersection model 7 and the direction relations based on projections 16 can be modelled in such a framework. STACLP is a constraint logic programming language where formulae can be annotated with labels (annotations) and where relations between these labels can be expressed by using constraints. Annotations are used to represent both time and space
The constraint operator of MedLan: Its efficient Implementation and Use
No full textThe Constraint Operator of MedLan: Its Efficient Implementation and Us
Using Temporary Integrity Constraints to Optimize Databases
No full textIntegrity constraints are usually assumed to be permanent properties that must be satisfied by any database state. However, there are many situations requiring also temporary constraints, that is, constraints that must hold only for a single database state. In this paper we propose a schema to define both permanent and temporary constraints, that supports efficient constraint checking and semantic query optimization. The proposed schema associates integrity constraints to rules and queries, and it uses methods, that were originally defined for permanent constraints only, to perform constraint checking and semantic query optimization
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