YES Problem: strict: s(a(x)) -> s(b(x)) b(b(x)) -> a(x) weak: f(s(x),y) -> f(x,s(y)) s(a(x)) -> a(s(x)) s(b(x)) -> b(s(x)) a(s(x)) -> s(a(x)) b(s(x)) -> s(b(x)) Proof: LPO Processor: precedence: f > b ~ s ~ a problem: strict: s(a(x)) -> s(b(x)) weak: s(a(x)) -> a(s(x)) s(b(x)) -> b(s(x)) a(s(x)) -> s(a(x)) b(s(x)) -> s(b(x)) Arctic Interpretation Processor: dimension: 1 interpretation: [s](x0) = x0, [a](x0) = 9x0, [b](x0) = x0 orientation: s(a(x)) = 9x >= x = s(b(x)) s(a(x)) = 9x >= 9x = a(s(x)) s(b(x)) = x >= x = b(s(x)) a(s(x)) = 9x >= 9x = s(a(x)) b(s(x)) = x >= x = s(b(x)) problem: strict: weak: s(a(x)) -> a(s(x)) s(b(x)) -> b(s(x)) a(s(x)) -> s(a(x)) b(s(x)) -> s(b(x)) Qed