Function sumo#extension_fn__extensionfn (sumo#Attribute -> sumo#class)  a unary_function that maps an attribute into the class whose condition for membership is the attribute
  type:  pm#unary_function_type  class of functions requiring a single argument; if R is functional, then if R(x -> y) and P(x -> z) then y=z
  type:  pm#partial_valued_relation_type  relation type that is not a total_valued_relation_type, i.e. just in case assigning values to every argument position except the last one does not necessarily mean that there is a value assignment for the last argument position; note that, if a sumo#relation is both a partial_valued_relation and a single_valued_relation, then it is a partial function
  supertype:  pm#relation_from_attribute_or_quality_or_measure (pm#attribute_or_quality_or_measure,*)
     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#relation_to_class (*,rdfs#class)
     supertype:  pm#relation_to_set_or_class (*,pm#set_or_class)
        supertype:  pm#relation_to_collection (*,pm#collection)
           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
           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#relation_to_type (*,pm#type)
        supertype:  pm#relation_to_collection (*,pm#collection)