The Unique Name Assumption (UNA) is a concept from ontology languages and description logics. In logics with the unique name assumption, different names always refer to different entities in the world[1]. The ontology language OWL does not make this assumption, but provides explicit constructs to express whether two names denote the same or distinct entities[2].
owl:sameAs is the OWL property that asserts that two given names or identifiers (e.g., URIs) refer to the same individual or entity.owl:differentFrom is the OWL property that asserts that two given names or identifiers (e.g., URIs) refer to different individuals or entities.