Consistent Assertion Sets
An assertion set is a set containing signature assertions and subtype assertions.
If ? is set of signature assertion define a ? *? b if the pair (a,b) is in the reflexive transitive closure of subtype assertions in ?.
? is inconsistent if, for example, any of following conditions hold. (10 altogether)
- ? *? contains a non-trivial directed cycle.
- a ?*? b, a.f:t*? r ? ?, b.f:t*?r ?? ? and r? r ?
- class purports to implement interface but does not defined or inherit a method defined in the interface.