He has published widely in the areas of philosophical, non-classical and spatial logic, ontology engineering, and Artificial Intelligence. He is a co-designer of the logic SROIQ underlying the web ontology language OWL 2.0, the E-connections technique used in modular knowledge representation, as well as the distributed ontology language DOL. Among others he was PC chair at FOIS 2014, co-organiser of the 4th World Congress on the Square of Opposition, and has been involved as organizer, chair, PC chair, or member of the steering committee in different workshops (SHAPES series, FOFAI, CAOS, WoMo series, etc.).