Relation pm#same_type_as (type,type)
  supertype:  relation_from_type  same_as (owl)
  equal:  equal (pm)
  subtype:  equivalent_class (class,class)  in WebKB, use the link '='
  subtype:  equivalent_property (binary_relation_type,binary_relation_type)  in WebKB, use the link '='