A shirtless skateboarder.
A skateboarder isn't wearing a shirt.
Not wearing a shirt is shirtless.
exists s1 x1.(a_topic(x1) & n_skateboarder(x1) & a_shirtless(s1) & Theme(s1,x1))
exists x1.(-exists e1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_wear(e1) & n_shirt(x2)) & n_skateboarder(x1))