The bird's feet are grasping the window tightly.
The bird is flying.
A bird cannot be flying and grasping the window tightly at the same time.
exists e1 s1 x1 x2 x3.(n_window(x3) & n_foot(x2) & of(x2,x1) & n_bird(x1) & a_tightly(s1) & Manner(e1,s1) & Theme(e1,x3) & Actor(e1,x2) & v_grasp(e1))
exists e1 x1.(n_bird(x1) & Actor(e1,x1) & v_fly(e1))