Validation Rules for Assessing and Improving SKOS Mapping Quality

The Simple Knowledge Organization System (SKOS) is popular for expressing controlled vocabularies, such as taxonomies, classifications, etc., for their use in Semantic Web applications. Using SKOS, concepts can be linked to other concepts and organized into hierarchies inside a single terminology system. Meanwhile, expressing mappings between concepts in different terminology systems is also possible. This paper discusses potential quality issues in using SKOS to express these terminology mappings. Problematic patterns are defined and corresponding rules are developed to automatically detect situations where the mappings either result in 'SKOS Vocabulary Hijacking' to the source vocabularies or cause conflicts. An example of using the rules to validate sample mappings between two clinical terminologies is given. The validation rules, expressed in N3 format, are available as open source.