This is the meta-level predicate for the 'rigid' classes of a theory (cf. Wiggins, 1980: within a given theory, if A is an instance of a !type class C in a conceivable situation s1, there is no conceivable s2 different from s1 in which A is not an instance of C). A type class is also countable (there is a part of something belonging to the class c which does not belong to c as well; in other terms, an instance of a !type class can be internally dishomogeneous). The first axiom implements rigidity, while the second implements countability.
(Inherited-Slot-Value Type The-Archetype Type) (=> (Type ?Self) (And (Exists (?Sit1) (And (Situation ?Sit1) (Context-Of ?Sit1 ?Self) (Forall (?X) (=> (Instance-Of ?X ?Self) (Not (Exists (?Sit2) (And (Situation ?Sit2) (Context-Of ?Sit2 ?Self) (Context-Of ?Sit2 ?X) (Different ?Sit2 ?Sit1) (Exists (?A) (And (Not (Instance-Of ?X ?Self)) (Holds-At ?Sit2 ?A)))))))))) (Forall (?Y) (=> (Instance-Of ?Y ?Self) (Exists (?Z ?Dishomog) (And (Instance-Of ?Z ?Dishomog) (Part-Of ?Z ?Y) (Conceptually-Different ?Self ?Dishomog)))))))