A skateboarder grinding a lip.
There are no people around.
A Skateboarder grinding a lip but there is no people around him.
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_grind(e1) & n_lip(x3) & (x1 = x2) & n_skateboarder(x1))
exists p1 x1.-exists x2.((x1 = x2) & r_around(x2) & n_people(x2))