]> 0.1: Created by Aldo Gangemi 0.2: Added object property 'requires' 1.1 added rdfs:isDefinedBy for all named entities http://www.ontologydesignpatterns.org/ont/dul/DUL.owl is required by is specialized by A partial order relation that holds between Concepts. It mainly represents the subsumption relation between e.g. a Concept and another Concept that is broader in extensional interpretation, but narrower in intensional interpretation. For example, the role PhDStudent specializes the role Student. requires A relation that holds between Concepts. Similarly to specializes, it represent the subsumption relation between e.g. a Concept and another Concept that is broader in extensional interpretation, but narrower in intensional interpretation. However, it represents the requisite that something classified by the first concept has to be classified by the second as well. For example, a designer might want to say that someone playing the Moderator role should be playing the Attendee role as well. This requisite is not equivalent to say e.g. that playing the Moderator role specializes playing the Mediator role. In this latter case, someone can be said a Mediator because it is a Moderator. On the contrary, in the first case someone is said to be a Moderator firstly because it is an Attendee. specializes A partial order relation that holds between Concepts. It mainly represents the subsumption relation between e.g. a Concept and another Concept that is broader in extensional interpretation, but narrower in intensional interpretation. For example, the role PhDStudent specializes the role Student.