Relationsumo#authors(?,?) type: pm#binary_predicate_typethe class of predicates relating two items - its valence is twotype: pm#asymmetric_relation_typean antisymmetric and irreflexive relationsupertype: pm#asymmetric_relation (?,?)this category only serves structuration purposes: it is instance of pm#asymmetric_relation_type which is not instance of pm#class_of_inheritable_relation_typesupertype: pm#irreflexive_relation__irreflexiverelation (?,?)this category only serves structuration purposes: it is instance of pm#irreflexive_relation_type which is not instance of pm#class_of_inheritable_relation_typesupertype: 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 categoriessupertype: pm#relation__related_thing__relatedthing___related_with (*)type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_typesupertype: pm#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_typesupertype: pm#binary_relation_with_particular_mathematical_property (?,?)