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