MAYBE
MAYBE
TRS:
 {
    f(mark(X1), X2) -> mark(f(X1, X2)),
  f(ok(X1), ok(X2)) -> ok(f(X1, X2)),
    active(f(X, X)) -> mark(f(a(), b())),
  active(f(X1, X2)) -> f(active(X1), X2),
        active(b()) -> mark(a()),
  proper(f(X1, X2)) -> f(proper(X1), proper(X2)),
        proper(a()) -> ok(a()),
        proper(b()) -> ok(b()),
       top(mark(X)) -> top(proper(X)),
         top(ok(X)) -> top(active(X))
 }
 DUP: We consider a non-duplicating system.
  Trs:
   {
      f(mark(X1), X2) -> mark(f(X1, X2)),
    f(ok(X1), ok(X2)) -> ok(f(X1, X2)),
      active(f(X, X)) -> mark(f(a(), b())),
    active(f(X1, X2)) -> f(active(X1), X2),
          active(b()) -> mark(a()),
    proper(f(X1, X2)) -> f(proper(X1), proper(X2)),
          proper(a()) -> ok(a()),
          proper(b()) -> ok(b()),
         top(mark(X)) -> top(proper(X)),
           top(ok(X)) -> top(active(X))
   }
  Fail