==> main.fstb MAY NOT TERMINATE. 

Cycle with transition(s):

t1 [A = 1, B = 1, C = 0, D = 1, A__o = 0, B__o = 0, C__o = 0, D__o = 0]
 -> t8 [A = 1, B = 1, C = 0, D = 1, A__o = 0, B__o = 0, C__o = 0, D__o = 0]

is likely to be an infinite loop.