YES (VAR x0 x1 x y z) (RULES f(i(a()),f(i(a()),f(i(a()),x0))) -> f(a(),f(a(),f(a(),x0))) f(a(),f(a(),f(a(),f(a(),x0)))) -> f(i(a()),f(i(a()),x0)) f(i(a()),f(i(a()),i(a()))) -> f(a(),f(a(),a())) f(b(),f(a(),x0)) -> f(i(a()),f(b(),x0)) f(a(),f(a(),f(a(),a()))) -> f(i(a()),i(a())) i(f(x0,x1)) -> f(i(x1),i(x0)) f(b(),a()) -> f(i(a()),b()) f(i(x0),f(x0,x1)) -> x1 f(x1,f(i(x1),x0)) -> x0 f(i(x0),x0) -> e() i(e()) -> e() f(e(),x0) -> x0 i(i(x0)) -> x0 i(b()) -> b() f(b(),f(b(),x0)) -> x0 f(b(),f(i(a()),x0)) -> f(a(),f(b(),x0)) f(b(),i(a())) -> f(a(),b()) f(b(),b()) -> e() f(x,e()) -> x f(x,i(x)) -> e() f(f(x,y),z) -> f(x,f(y,z)) ) (COMMENT Termination is shown by KBO with weight w0 = 1 w(f) = 0 w(i) = 0 w(e) = 2 w(a) = 2 w(b) = 7 and precedence: i > f > e > a > b )