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Title: The modular structure of an ontology : atomic decomposition and its applications
Author: Del Vescovo, Chiara
ISNI:       0000 0004 2740 745X
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2013
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Ontologies are descriptions of the knowledge about a domain of interest encoded in computer processable languages, e.g., Description Logics, which are decidable fragments of First Order Logic. The main aim of ontologies is to define unambiguous vocabularies to facilitate knowledge sharing and integration. A critical issue with ontologies consists of their increasing complexity. To address this problem several notions of modularity have been recently proposed. Modularity notions can help in two ways: 1) If we know what sub-part of the ontology we want to work with, obtaining the appropriate module will allow us to work with that sub-part in a principled way; 2) a notion of module might induce a modular structure which allows users to explore the entire ontology in a sensible manner (perhaps finding appropriate sub-parts to work on). However, the most popular notion --- locality based modules --- while excelling at modular extraction have thus far resisted attempts to induce a modular structure. Indeed, due to their nature, locality based modules tend to occur in unfeasible numbers in ontologies. We tackle this problem by identifying basic building blocks of modules as sets of axioms which 'cling together', that is, sets of axiom such that if any element appears in a module, then all the rest due. This notion of an 'atom'' proves key to defining a useful family of locality based modular structures, the (Labelled) Atomic Decompositions ((L)ADs). In this thesis, we define (L)AD and explore its properties. We show that ADs are efficiently computable and, with appropraite labellings, provide a reasonably terse representation of the entire set of locality based modules. From ADs, we are able to distinguish so-called "genuine" modules, i.e., modules that cannot be decomposed further as the union of two or more modules. Finally, we explore several of the applications to which (L)ADs have been applied including module extraction, ontology comprehension, and modular reasoning.
Supervisor: Sattler, Ulrike; Parsia, Bijan Sponsor: EPSRC
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Ontologies ; Modularity ; Modular Structure