 its range. A function is either unary, binary, ternary, or whatever (see #$functionalArity; but cf. #$relationalArity), depending on the nature of the members of its domain. In general, the domain of an N-ary function is a set of ordered N-tuples (construed in CycL as #$Lists of length N). The function is said to take the items from any of these N-tuples as its N _arguments_ and to return a member of its range as its corresponding _value_. A key specialization of #$Function-MathematicalObject is #$FixedAri