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)))))))