Relation pm#relation_from_or_to_WordNet_type (*)
  supertype:  pm#binary_relation  in WebKB, most relation types are binary and some have a variable number of arguments (as in KIF), hence this type is currently only specialized by types that I do not want to see as direct subtypes of pm#relation
  subtype:  pm#menu (pm#meal_shop,#food_or_beverage)