MAYBE We are left with following problem, upon which TcT provides the certificate MAYBE. Strict Trs: { f(c(s(x), y)) -> f(c(x, s(y))) , f(c(s(x), s(y))) -> g(c(x, y)) , g(c(x, s(y))) -> g(c(s(x), y)) , g(c(s(x), s(y))) -> f(c(x, y)) } Obligation: innermost runtime complexity Answer: MAYBE The input cannot be shown compatible Arrrr..