+
+-- If cidr1 properly contains cidr2, then by definition cidr2
+-- does not properly contain cidr1.
+prop_contains_proper_intransitive :: Cidr -> Cidr -> Property
+prop_contains_proper_intransitive cidr1 cidr2 =
+ (cidr1 `contains_proper` cidr2) ==>
+ (not (cidr2 `contains_proper` cidr1))