Relation pm#relation_with_particular_property (*)  this rather fuzzy type permits to group categorization schemes less common than those covered by the previous sibling categories
  subtype:  pm#relation_with_particular_mathematical_property {pm#binary_relation pm#ternary_relation pm#quaternary_relation pm#relation_with_variable_arity}  pm#relation_using_a_world_as_argument  lis#relationship  lis#class_of_relationship  lis#class_of_class_of_relationship
  >part of:  pm#relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type