This monograph discusses the structural matching of description logic ontologies. Our belief is that structural matches of ontologies hold some deeper information about the similarities between different ontologies than a mere syntactic match. Ontologies are parsed into attributed trees where nodes represent the concepts and edges represent the relationship between concepts. T h e match between any two nodes is calculated by traversing the derived trees in an efficient algorithm that limit the number of comparisons to be performed by eliminating unnecessary comparison in order to maintain a...