Checker (sometimes?) forgets to do the "cluster rounding up".
Test case
(taken from the Hagenberg course)
having the cluster being_T1 -> T_0 TopSpace; (YELLOW13) in environmnt, following is accepted:
T is being_T1 TopSpace implies T is T_0;
while following not (even though T is properly reserved for TopSpace?):
T is being_T1 implies T is T_0;