Stanislav Pokraev Rogier Brussee Extending OWL with Maximal Subproperties: An Approach to Define Qualified Cardinality Restrictions and Reflexive Properties. 2005 OWLED http://ceur-ws.org/Vol-188/sub33.pdf conf/owled/2005 db/conf/owled/owled2005.html#PokraevB05