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