Our Meth8 logic model checker invalidates []( []A > A) = []A by proving only one model in five (Model 2.2 only)..

Here is the theorem output:

Test input as processed is: (#(#A>A)=#A)

FCNT is: False, Contingent, Non contingent, True.  UIPE is: Unevaluated, Improper, Permissible, Evaluated.

#(#A>A)=#A

Model 1               Model 2.1             Model 2.2             Model 2.3.1           Model 2.3.2          

CCTT CCTT CCTT CCTT   UIPE UIPE UIPE UIPE   EEEE EEEE EEEE EEEE   PEPE PEPE PEPE PEPE   IIEE IIEE IIEE IIEE