TRS: {f(x, a(b(y))) -> f(a(b(x)), y), f(x, b(c(y))) -> f(b(c(x)), y), f(x, c(a(y))) -> f(c(a(x)), y), f(a(x), y) -> f(x, a(y)), f(b(x), y) -> f(x, b(y)), f(c(x), y) -> f(x, c(y))} Fail