Efficient Inferencing for the Description Logic Underlying OWL EL

The recent OWL 2 W3C recommendation includes the lightweight ontology language OWL EL which is semantically based on an extension of the EL description logic (DL). It is widely assumed that inferencing in OWL EL is possible in polynomial time, but it is not obvious how to extend existing reasoning procedures for EL accordingly. We set out to close this gap by developing inferencing methods for SROEL(⊓,×) – a DL that subsumes the main features of OWL EL. We present a framework for studying materialisation calculi based on datalog, and we use it to investigate the resource requirements for inferencing. We can show that certain SROEL(⊓,×) feature combinations must lead to increased space upper bounds in any materialisation calculus, suggesting that efficient implementations are easier to obtain for suitably chosen fragments of SROEL(⊓,×).