Relation rdfs#is_defined_by (?,pm#entity)  in WebKB, pm#definition SHOULD BE USED INSTEAD
  supertype:  rdfs#see_also__seealso
  equal:  daml#is_defined_by
  subtype:  pm#definition (?,pm#description_content/medium/container)  see also #definition
     subtype:  rst#definition (pm#description_content/medium/container,pm#description_content/medium/container)  a logical relation should be used instead of this relation