YES proof: The input problem is infeasible because [1] the following set of Horn clauses is satisfiable: min(xs) = y & le(x, y) = false ==> min(cons(x, xs)) = y min(xs) = y & le(x, y) = true ==> min(cons(x, xs)) = x min(cons(x, nil)) = x le(s(x), s(y)) = le(x, y) le(0, s(y)) = true le(x, 0) = false min(x2) = y & le(x1, y) = true & min(x2) = x3 & le(x1, x3) = false ==> true__ = false__ true__ = false__ ==> \bottom This holds because [2] the following E does not entail the following G (Claessen-Smallbone's transformation (2018)): E: g1(false, x, xs) = min(xs) g1(le(x, min(xs)), x, xs) = min(cons(x, xs)) g1(true, x, xs) = x le(0, s(y)) = true le(s(x), s(y)) = le(x, y) le(x, 0) = false min(cons(x, nil)) = x t1(le(x1, min(x2)), le(x1, min(x2))) = true__ t1(true, false) = false__ t2(false__) = true__ t2(true__) = false__ G: true__ = false__ This holds because [3] the following ground-complete ordered TRS entails E but does not entail G: g1(false, X0, X1) -> min(X1) g1(le(X0, min(nil)), X0, nil) -> X0 g1(true, X0, X1) -> X0 le(0, s(X0)) -> true le(X0, 0) -> false le(s(X0), s(X1)) -> le(X0, X1) min(cons(X0, X1)) -> g1(le(X0, min(X1)), X0, X1) t1(Z1, Z1) -> true__ t1(false, false) -> true__ t1(true, false) -> false__ t2(false__) -> true__ t2(true__) -> false__ with the LPO induced by 0 > true > cons > le > nil > false > g1 > min > s > t2 > t1 > false__ > true__