MAYBE
MAYBE
TRS:
 {ap(ap(ff(), x), x) -> ap(ap(x, ap(ff(), x)), ap(ap(cons(), x), nil()))}
 DUP: We consider a duplicating system.
  Trs:
   {ap(ap(ff(), x), x) -> ap(ap(x, ap(ff(), x)), ap(ap(cons(), x), nil()))}
  Fail