Function CARDINALITY

Returns the number of elements in a set.

Arity: 2

Domain: Set

Range: Integer

Axioms:

(<=> (Cardinality ?Set ?Integer)
     (And (Set ?Set)
          (Exists (@Elements)
                  (And (= ?Set (Setof @Elements))
                       (= ?Integer (Length (Listof @Elements)))))))

• Defined in theory: Kif-extensions
• Source code: kif-extensions.lisp

Notes:

• not explicitly defined in the KIF 3.0 spec