MAYBE Proof: ConCon could not decide if this system is quasi-decreasing. \cite{O02}, p. 214, Proposition 7.2.50 does not apply. System R transformed to U(R). Call external tool: ttt2 - trs 30 Input: lt(x, 0) -> false lt(0, s(y)) -> true lt(s(x), s(y)) -> lt(x, y) ?1(true, x, y, ys) -> cons(y, cons(x, ys)) cons(x, cons(y, ys)) -> ?1(lt(x, y), x, y, ys) The external tool could not decide termination.