Published by the IEEE Computer Societyother controlled vocabularies) specific to fields, institutions, and even collections. The desire to make CH resources available to the general public (for example, see www. europeana.eu) increases the need to facilitate interoperability across different contexts.By providing representational standards such as the Simple Knowledge Organization System (SKOS; www.w3.org/2004/02/skos) and generic tool support, the Semantic Web community has taken a prominent role in this facilitation. Its ontology-matching branch aims at developing technology to produce alignments-that is, sets of semantic mappings bet ween elements from different vocabularies. 1 One can exploit alignments, for instance, to access a collection via thesauri it is not originally indexed with, to interconnect distributed, differently annotated collections on the object level, or to merge two thesauri to rationalize thesaurus maintenance.Unfortunately, our experience shows that existing matching tools often do not perform well in CH applications. 2 We believe part of the problem is that they strive for generality. To this end, we argue that the generation and evaluation of thesaurus alignments must take into account well-understood realworld application contexts and their specific requirements.
Ontology MatchingOntology matching aims at determining the semantic relations bet ween elements of two given knowledge organization systems (for example, ontologies and thesauri). 1 The set of semantic relations usually comprises concept equivalence, hierarchical concept links