An integer range is a class of integers specified by lower and upper bounds. Instances of an integer-range are integers.
(<=> (Integer-Range ?Class) (And (Class ?Class) (Subclass-Of ?Class Integer) (Value-Cardinality ?Class I-Lower-Bound 1) (Value-Cardinality ?Class I-Upper-Bound 1) (Forall (?I) (=> (Instance-Of ?I ?Class) (And (=< (I-Lower-Bound ?Class) ?I) (=< ?I (I-Upper-Bound ?Class)))))))