YES (VAR x0 x1 x2 x y) (RULES f(*(x0,x1)) -> g(x0) *(x0,*(x1,x2)) -> *(x0,g(x1)) g(*(x0,x1)) -> f(x1) *(*(x2,x0),x1) -> *(f(x0),x1) *(x0,f(x1)) -> *(x0,x1) *(x0,g(x0)) -> g(x0) g(f(x0)) -> f(x0) f(g(x0)) -> g(x0) *(f(x0),x0) -> f(x0) f(f(x0)) -> f(x0) g(g(x0)) -> g(x0) *(f(x0),g(x0)) -> x0 *(g(x),y) -> *(x,y) ) (COMMENT Termination is shown by EKBO with interpretations on natural numbers *_A(x1,x2) = x1 + x2 + 2 f_A(x1) = x1 + 1 g_A(x1) = x1 + 1 *#_A(x1,x2) = x2 f#_A(x1) = 0 weights w0 = 1 w(*) = 1 w(f) = 1 w(g) = 1 and precedence: g > * > f )