Snorocket 2.0: Concrete Domains and Concurrent Classification. Snorocket is a high-performance ontology reasoner that sup- ports a subset of the OWL EL profile. In the newest version, additional expressive power has been added to support concrete domains, enabling the classification of ontologies that use these constructs. Also, the rea- soning algorithm has been modified to support concurrent classification. This feature is important because it enables the use of the full processing power available in modern multi-processor hardware.