WOWL: Tailoring OWL for the Web of Data Birte Glimm 1 , Aidan Hogan 2 , and Axel Polleres 2,3 1 Department of Computer Science, The University of Oxford, United Kingdom 2 Digital Enterprise Research Institute, National University of Ireland Galway, Ireland 3 Siemens AG ¨ Osterreich, Siemensstrasse 90, 1210 Vienna, Austria Abstract. One of the attractive features of Linked Data is the simplicity of the underlying idea, which encourages uptake by a wide range of parties. RDF(S) and OWL provide standard semantics to express explicit and implicit knowl- edge, while the SPARQL query language allows for querying the available data. When processing Linked Data however, most systems work on a syntactic level; the meaning of special terms from the RDFS and OWL vocabularies such as rdfs:subClassOf or owl:FunctionalProperty is only partially or not at all taken into account. One reason for this is that reasoning, in particular for OWL, is arguably too complex for the Web of Data. The OWL 2 RL profile addresses these issues to some extent by providing a set of rules that (partially) axiomatise the semantics of several RDF(S) and OWL constructs. However, OWL 2 RL con- tains various features which are unintuitive to express in RDF, as well as costly to implement and fully support. Thus, we propose WOWL: a significantly sim- plified subset of OWL 2 RL based on an analysis of the most commonly used modelling features in current Linked Data. 1 Introduction Under the initial impetus of the Linking Open Data project – and guided by the Linked Data principles [2] and associated best-practices – a rich vein of openly-available struc- tured data has been published on the Web using Semantic Web standards. Publishing RDF on the Web is no longer confined to academia and hobbyists: the current “Web of Data” now features exports from various corporate and commercial bodies (e.g., BBC, New York Times, Freebase, BestBuy), online communities (e.g., Wikipedia, Geon- ames), life-science corpora (e.g., DrugBank, Linked Clinical Trials) and governmental bodies (e.g., data.gov, data.gov.uk, EuroStat). The “Linked Open Data cloud” now de- picts 203 interlinked datasets, which together consist of tens of billions of RDF triples. 4 Although Linked Data adoption still pales in comparison with the Web as a whole, the amount of RDF published on the Web and the parties engaged in such efforts repre- sents a significant leap forward. This progress is perhaps attributable to Linked Data’s bottom-up, incrementalist approach to the Semantic Web standards: so far higher lev- els of the traditional Semantic Web stack – such as ontologies, logic, proof, trust and cryptography – have been largely downplayed. The same challenges originally envisaged for the Semantic Web are now being re- alised for the Web of Data. Although RDF offers standard syntaxes and a common data- model for disseminating structured information, heterogeneity in how resources are 4 http://richard.cyganiak.de/2007/10/lod/