MAYBE

We are left with following problem, upon which TcT provides the
certificate MAYBE.

Strict Trs:
  { a__f(X1, X2) -> f(X1, X2)
  , a__f(g(X), Y) -> a__f(mark(X), f(g(X), Y))
  , mark(g(X)) -> g(mark(X))
  , mark(f(X1, X2)) -> a__f(mark(X1), X2) }
Obligation:
  innermost runtime complexity
Answer:
  MAYBE

The input cannot be shown compatible

Arrrr..