MAYBE We are left with following problem, upon which TcT provides the certificate MAYBE. Strict Trs: { half(0()) -> 0() , half(s(0())) -> 0() , half(s(s(x))) -> s(half(x)) , lastbit(0()) -> 0() , lastbit(s(0())) -> s(0()) , lastbit(s(s(x))) -> lastbit(x) , zero(0()) -> true() , zero(s(x)) -> false() , conv(x) -> conviter(x, cons(0(), nil())) , conviter(x, l) -> if(zero(x), x, l) , if(true(), x, l) -> l , if(false(), x, l) -> conviter(half(x), cons(lastbit(x), l)) } Obligation: innermost runtime complexity Answer: MAYBE The input cannot be shown compatible Arrrr..