Relation pm#exclusive_class__exclusiveclas (rdfs#class,rdfs#class)  the 2 classes have no common subtype/instance; in WebKB, use the link '!'
  supertype:  pm#relation_to_another_class  pm#disjoint  pm#exclusive_type  pm#different
  equal:  owl#disjoint_with (pm)
  subtype:  pm#complement_class (rdfs#class -> rdfs#class)  if something is not in one of the classes, then it is in the other, and vice versa; in WebKB, use the link '/'