REL is an OWL2-EL reasoner, based on an optimised implementation of the CEL algorithm. It is developed by Yuan Ren in Aberdeen University as a component of the TrOWL infrastructure. The long-term objective of REL is to provide efficient, reliable and convenient reasoning services.
Currently REL supports TBox classification and conjunctive query answering for EL+ ontologies. A beta version of REL and examples can be downloaded soon.
A coming version of REL will provide tractable and soundness-preserving TBox reasoning for very expressive ontology languages including OWL-DL and OWL2-DL.