YES (VAR x0 x1 x y z) (RULES f(a(),f(a(),f(a(),x0))) -> f(b(),f(a(),f(a(),f(b(),x0)))) f(a(),f(a(),a())) -> f(b(),f(a(),f(a(),b()))) i(f(x1,x0)) -> f(i(x0),i(x1)) f(i(x0),x0) -> f(b(),b()) i(a()) -> f(b(),f(a(),b())) f(i(x0),f(x0,x1)) -> x1 i(i(x0)) -> x0 i(b()) -> b() f(a(),f(b(),f(a(),x0))) -> f(b(),x0) f(b(),f(b(),x0)) -> x0 f(a(),f(b(),a())) -> b() f(x1,f(i(x1),x0)) -> x0 f(x,f(b(),b())) -> x e() -> f(b(),b()) f(x,i(x)) -> f(b(),b()) f(f(x,y),z) -> f(x,f(y,z)) ) (COMMENT Termination is shown by LPO with precedence: i > a > e > b > f )