Relation pm#exclusive_type__exclusivetype (type,type)  in WebKB, use the '!' link
  supertype:  relation_from_type  type of relations from a concept/relation type, i.e. in RDFS terminology, from a class or a property
  equal:  disjoint (pm)
  subtype:  exclusive_class__exclusiveclas (class,class)  the 2 classes have no common subtype/instance; in WebKB, use the link '!'
     subtype:  complement_class (class -> class)  if something is not in one of the classes, then it is in the other, and vice versa; in WebKB, use the link '/'
  subtype:  closed_exclusion (type -> type)  the '/' link in the FT notation:  the two linked types either are respectively identical to pm#thing and pm#nothing (they are "complement types") or they subtype a same type and form a complete subtype partition
     subtype:  complement_type (type -> type)  a supertype of owl#complement_of which can only connect RDFS/OWL classes
        subtype:  complement_class (class -> class)  if something is not in one of the classes, then it is in the other, and vice versa; in WebKB, use the link '/'