Ph.D. Dissertation Defense “DISTRIBUTED RULE-BASED ONTOLOGY REASONING” By Raghava Mutharaju

Ph.D. Committee:  Drs. Pascal Hitzler, Advisor, Prabhaker Mateti, Derek Doran, Freddy Lecue (Accenture Technology Labs, Ireland), and Frederick Maier (Institute for AI, University of Georgia) 

ABSTRACT:

The vision of the Semantic Web is to provide structure and meaning to the data on the Web. Knowledge representation and reasoning play a crucial role in accomplishing this vision. OWL (Web Ontology Language), a W3C standard, is used for representing knowledge. Reasoning over the ontologies is used to derive logical consequences. All the existing reasoners run on a single machine, possibly using multiple cores. The amount of available data is increasing at a rapid rate and single machine reasoners will not be able to keep up with this growth rate. They are constrained by the memory and computing resources available on a single machine. In this dissertation, we use distributed computing to find scalable approaches to ontology reasoning. Four different approaches to ontology reasoning that make use of a cluster of machines are discussed. They all work on a tractable profile of OWL with a polynomial reasoning time, called OWL 2 EL. Along with the description of the algorithms, optimizations and evaluation results of the four distributed reasoners, we also put in recommendations for the best choice of reasoners for different scenarios.