Function sumo#power_set_fn__powersetfn (sumo#set_or_class -> sumo#set_or_class)  maps the argument to the set_or_class of all its subclasses
  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#total_valued_relation_type  when there exists an assignment for the last argument position of the relation given any assignment of values to every argument position except the last one; note that declaring a relation to be both a total_valued_relation and a single_valued_relation means that it is a total function
  supertype:  pm#relation_to_another_set_or_class (pm#set_or_class,pm#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:  pm#relation_between_collections (pm#collection,pm#collection+)
        supertype:  pm#relation_from_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#relation__related_thing__relatedthing___related_with (*)  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type
           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 
                 supertype:  pm#relation__related_thing__relatedthing___related_with (*)  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type
        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#relation_to_set_or_class (*,pm#set_or_class)
        supertype:  pm#relation_to_collection (*,pm#collection)


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