YES linear polynomial interpretations on natural numbers: add_A(x1,x2) = x1 + x2 s_A(x1) = x1 0_A = 0 gcd_A(x1,x2) = x1 + x2 leq_A(x1,x2) = 0 false_A = 1 the condition leq(x2,add(x,x2)) ->> false() is unsatisfiable for all substitutions.