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