Relation aktp#sub-area-of (pm#domain,pm#domain)
  supertype:  aktp#relation_about_an_area_of_interest (?,?)
     supertype:  aktp#relation (?,?)
        supertype:  pm#relation_coming_from_an_ontology (*)
           supertype:  pm#relation_for_an_application (*)  relation introduced by an application
              supertype:  pm#relation_playing_a_special_role (*)  this type permits to categorize relations according to their roles ; this is a traditional but quite subjective way of categorizing relations
                 supertype:  pm#relation__related_thing__relatedthing___related_with (*)  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type
  supertype:  pm#subdomain__true-subdomain (pm#domain,pm#domain)  in WebKB-2, ">part" is an abbreviation of this relation since it is not  
            a part relation nor a specialization relation but a mix of both; 
            for details, see http://www.webkb.org/kb/it/o_domain/d_field_of_study.html
     supertype:  pm#relation_from_a_domain__thing_in_domain (pm#domain,?)
        supertype:  pm#domain_related_relation__domain-related-thing (?,?)
           supertype:  pm#relation_playing_a_special_role (*)  this type permits to categorize relations according to their roles ; this is a traditional but quite subjective way of categorizing relations
     supertype:  pm#relation_to_a_domain__sub-domain_or_object-subdomain (?,pm#domain)
        supertype:  pm#domain_related_relation__domain-related-thing (?,?)


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