MAYBE
ignored inputs:
(COMMENT non-uniform system with a non-joinable trivial critical pair )
(COMMENT Lemma 56 of [ FG07 , doi:10.1016/j.ic.2006.12.002 ] )

NRS:
   [ (0):  |- (f <b>) -> a,
     (1): a#X |- []X -> [a][]X ]
variable conditions not hold
result: MAYBE
time: 0 msec.