Function pm#exterior__in (spatial_object -> spatial_object)
  inverse:  interior
  supertype:  location (spatial_object,spatial_object)
     supertype:  relation_to_another_spatial_object (spatial_object,spatial_object)
        supertype:  relation_from_spatial_object (spatial_object,*)
           supertype:  spatial_relation_from_entity_with_spatial_feature (object,*)
              supertype:  relation_from/to_thing_of_common_kind (*)  this type permits to categorize relations according to their signatures and hence offers (i) a concise way to set essential exclusion relations, and (ii) a systematic and easy-to-follow categorization
                 >part of:  relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type
        supertype:  relation_to_spatial_object (*,spatial_object)  in WebKB, prefer using relations "from" a spatial object
           supertype:  spatial_relation_to_entity_with_spatial_feature (*,object)
              supertype:  relation_from/to_thing_of_common_kind (*)  this type permits to categorize relations according to their signatures and hence offers (i) a concise way to set essential exclusion relations, and (ii) a systematic and easy-to-follow categorization
        supertype:  where_relation__whererelation (*)  where, from/to where, ...
           supertype:  wh-/how_relation (*)  this type permits to categorize relations according to the usual who/what/why/where/when/how questions ; this is a traditional but very subjective and ineffective way of categorizing relations 
              >part of:  relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type