YES proof: The input problem is infeasible because [1] the following set of Horn clauses is satisfiable: y' = y & y'' = y ==> f(y', h(y'')) = g(y) x' = x & x'' = x ==> f(x', x'') = g(x) x1 = x & h(x2) = x & x1 = x3 & x2 = x3 ==> true__ = false__ true__ = false__ ==> \bottom This holds because [2] the following E does not entail the following G (Claessen-Smallbone's transformation (2018)): E: f(x, x) = g(x) f(y, h(y)) = g(y) t1(h(x3), x3) = true__ t1(x3, x3) = 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: f(y, h(y)) -> f(y, y) g(x) -> f(x, x) t1(h(x3), x3) -> true__ t1(x3, x3) -> false__ t2(false__) -> true__ t2(true__) -> false__ with the LPO induced by t2 > t1 > h > g > f > false__ > true__