An active, ontology-driven network service for Internet collaboration

Web portals have emerged as an important means of collaboration on the WWW, and the integration of ontologies promises to make them more accurate in how they serve users’ collaboration and information location requirements. However, web portals are essentially a centralised architecture resulting in difficulties supporting seamless roaming between portals and collaboration between groups supported on different portals. This paper proposes an alternative approach to collaboration over the web using ontologies that is de-centralised and exploits content-based networking. We argue that this approach promises a user-centric, timely, secure and location-independent mechanism, which is potentially more scaleable and universal than existing centralised portals

The Analysis of Resource Use in the λ-Calculus by Type Inference

This thesis is concerned primarily with the definition and semantics of resource use in the λ-calculus and the implicational fragment of intuitionistic propositional logic. A secondary aim is the subsequent derivation of a type system which can infer the expected reduction behaviour of functions upon their arguments. The term resource use refers to the view of arguments as the resources a function requires to produce a result. In this thesis, resource use will be taken to mean a property of the formal parameter of a function that describes the use that the function will make of arguments substituted for the parameter. Knowledge of the resource use of a function parameter can lead to many practical benefits in the efficient compilation of functional programs. Recent research has investigated the derivation of resource use information using type inference. Types inferred for functions contain resource use information about the way that arguments will be evaluated when applied to those functions. However, the justification of the correctness of these type systems relies on the given interpretation of type expressions as sets of terms possessing those types. The main contribution of this thesis is the definition of resource use in both the λ-calculus and in the implicational fragment of intuitionistic propositional logic that corresponds to the typed λ-calculus under the Curry-Howard isomorphism. We are able to demonstrate the correspondence of resource use between (typed) λ-terms and the proofs in intuitionsitic logic, though we find that this correspondence is not up to equivalence. Subsequently, we derive a type system for inferring resource use in λ-terms and also discuss the implementation of the type system. We find that we are unable to apply previously-used methods of unification over types containing resource use information when the range of resource use information is expanded

Finding Relevant Web Pages Through Equivalent Hyperlinks

Abstract. Finding pages on the web that are relevant to some user-defined criteria is a longestablished area of research. Early work on search engines concentrated on the textual content of web pages to find relevant pages, but in recent years, the analysis of information encoded in hyperlinks has been used to vastly improve search engine performance. This paper presents a variation on the use of link analysis for automatically categorizing web pages, by defining a similarity measure and search technique based on hyperlinks. This measure is used to categorize hyperlinks themselves, rather than web pages. This allows us to, given a particular hyperlink, to find others like it in terms of its context and referred-to web pages. We have implemented a prototype version of the technique as a browser application. Initial tests appear to show that the method, as implemented in our browser, returns precise, well-focussed results.

Combining Inheritance and Parametric Polymorphism in a Functional Database Language

. We consider extending a functional database language to support subtyping, inheritance and method overloading. We do so by extending previous work on type inference with subtypes for the pure calculus to cater for structured types, ML-style parametric polymorphism and overloaded function definitions. We attach semantics to overloaded functions by developing a generalisation of best-fit pattern-matching. Although developed for a specific language, our approach is applicable to other functional database languages, for example languages with a functional data model. 1 Introduction Two major trends in recent database research have been deductive databases and object-oriented databases. Deductive databases extend the relational data model with rules that enable the derivation of intentional relations from the stored, extensional, relations. Object-oriented databases typically start off with a semantic data model [HK87] supporting object identity and complex objects, and extend it with f..