MAYBE We are left with following problem, upon which TcT provides the certificate MAYBE. Strict Trs: { p(0()) -> 0() , p(s(x)) -> x , le(0(), y) -> true() , le(s(x), 0()) -> false() , le(s(x), s(y)) -> le(x, y) , minus(x, 0()) -> x , minus(x, s(y)) -> if(le(x, s(y)), 0(), p(minus(x, p(s(y))))) , if(true(), x, y) -> x , if(false(), x, y) -> y } Obligation: innermost runtime complexity Answer: MAYBE The input cannot be shown compatible Arrrr..