MAYBE We are left with following problem, upon which TcT provides the certificate MAYBE. Strict Trs: { D(t()) -> 1() , D(constant()) -> 0() , D(+(x, y)) -> +(D(x), D(y)) , D(*(x, y)) -> +(*(y, D(x)), *(x, D(y))) , D(-(x, y)) -> -(D(x), D(y)) } Obligation: innermost runtime complexity Answer: MAYBE The input cannot be shown compatible Arrrr..