Relation pm#relation_to_another_class (class,class+)
  subtype:  sub_class_of  equivalent_class  exclusive_class  restricted_by  disjoint_decomposition  exhaustive_decomposition
  supertype:  relation_from_class_to_collection (class,collection)
     supertype:  relation_from_type_to_collection (type,collection)
        supertype:  relation_between_collections (collection,collection+)
           supertype:  relation_from_collection (collection,*)
              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:  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 
                    >part of:  relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type
           supertype:  relation_to_collection (*,collection)
              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:  what_relation (*)
        supertype:  relation_from_type (type,*)  type of relations from a concept/relation type, i.e. in RDFS terminology, from a class or a property
           supertype:  relation_from_collection (collection,*)
     supertype:  relation_from_class (class,*)
        supertype:  relation_from_type (type,*)  type of relations from a concept/relation type, i.e. in RDFS terminology, from a class or a property
  supertype:  relation_to_another_set_or_class (set_or_class,set_or_class+)  this category is needed to group SUMO relations between classes which cannot be subtype of pm#relation_from_type because their signatures curiously also involve sets
     supertype:  relation_between_collections (collection,collection+)
     supertype:  relation_to_set_or_class (*,set_or_class)
        supertype:  relation_to_collection (*,collection)