Relation pm#physical_part (physical_entity,physical_entity)
  supertype:  spatial_part__spatialpart (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
     supertype:  part (?,?)
        supertype:  part_or_parts (?,?)
           supertype:  mereological_relation (?,*)
              supertype:  relation_playing_a_special_role (*)  this type permits to categorize relations according to their roles ; this is a traditional but quite subjective 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
              supertype:  what_relation (*)
                 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 
        supertype:  partial_ordering_relation (?,?)  this category only serves structuration purposes: it is instance of pm#partial_ordering_relation_type which is not instance of pm#class_of_inheritable_relation_type
           supertype:  reflexive_relation__reflexiverelation (?,?)  this category only serves structuration purposes: it is instance of pm#reflexive_relation_type which is not instance of pm#class_of_inheritable_relation_type
              supertype:  binary_relation_with_particular_mathematical_property (?,?)
                 supertype:  relation_with_particular_mathematical_property (*)
                    supertype:  relation_with_particular_property (*)  this rather fuzzy type permits to group categorization schemes less common than those covered by the previous sibling categories
                       >part of:  relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type
           supertype:  antisymmetric_relation__antisymmetricrelation (?,?)  this category only serves structuration purposes: it is instance of pm#antisymmetric_relation_type which is not instance of pm#class_of_inheritable_relation_type
              supertype:  binary_relation_with_particular_mathematical_property (?,?)
           supertype:  transitive_relation (?,?)  this category only serves structuration purposes: it is instance of pm#transitive_relation_type which is not instance of pm#class_of_inheritable_relation_type
              supertype:  binary_relation_with_particular_mathematical_property (?,?)