Relation pm#equivalence__equivalentTo___iff__iff (pm#description,pm#description)
  supertype:  pm#implication__then___therefore__therefore (pm#description,pm#description)
     supertype:  pm#contextualizing_logical_relation__contextualizinglogicalrelation (pm#description,pm#description)
        supertype:  pm#logical_relation__logicalrelation (pm#description,pm#description)
           supertype:  pm#relation_from_description (pm#description,*)
              supertype:  pm#relation_from_description_content/medium/container (pm#description_content/medium/container,*)
                 supertype:  pm#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:  pm#relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type
        supertype:  pm#contextualizing_relation__contextualizingrelation (pm#description,*)
           supertype:  pm#relation_from_description (pm#description,*)
           supertype:  pm#what_relation (*)
              supertype:  pm#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:  pm#relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type
  supertype:  pm#equivalence_relation__equivalencerelation (?,?)  this category only serves structuration purposes: it is instance of pm#equivalence_relation_type which is not instance of pm#class_of_inheritable_relation_type
     supertype:  pm#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:  pm#binary_relation_with_particular_mathematical_property (?,?)
           supertype:  pm#relation_with_particular_mathematical_property (*)
              supertype:  pm#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:  pm#relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type
     supertype:  pm#symmetric_relation__symmetricrelation (?,?)  this category only serves structuration purposes: it is instance of pm#symmetric_relation_type which is not instance of pm#class_of_inheritable_relation_type
        supertype:  pm#binary_relation_with_particular_mathematical_property (?,?)
     supertype:  pm#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:  pm#binary_relation_with_particular_mathematical_property (?,?)