Function ARITY

Slots on this function:

Arity is the number of arguments that a relation can take. If a relation can take an arbitrary number of arguments, its arity is undefined. For example, a function such as `+' is of undefined arity; its last formal argument is specified with a sequence variable. The arity of a function is one more than the number of arguments it can take, in keeping with the unified treatment of functions and relations. The arity of the empty relation (i.e., with no tuples) is undefined.
Arity: 2
Domain: Relation
Range: Integer


(<=> (Arity ?Relation ?N)
     (And (Relation ?Relation)
          (Not (Empty ?Relation))
          (Integer ?N)
          (Forall (?Tuple)
                  (=> (Member ?Tuple ?Relation)
                      (= (Length ?Tuple) ?N)))))