A cowboy is riding a horse whilst spinning a lasso around.
A man on a horse spins some rope around.
Spinning a lasso does not necessarily mean spins some rope.
exists e1 e2 s1 x1 x2 x3 x4.(for(e1,e2) & Theme(e2,x4) & Actor(e2,x1) & v_spin(e2) & n_lasso(x4) & a_around(s1) & Theme(s1,x4) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_whilst(x2) & of(x2,x3) & n_horse(x3) & n_cowboy(x1))
exists e1 s1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_spin(e1) & n_rope(x3) & a_around(s1) & Theme(s1,x3) & on(x1,x2) & n_horse(x2) & n_man(x1))