A view from the top of a skateboarder at the top of a ramp.
There is someone skateboarding without a helmet on.
You can not infer they do not have a helmet.
exists x1 x2 x3 x4.(n_top(x2) & n_top(x2) & a_topic(x1) & from(x1,x2) & of(x2,x3) & at(x3,x2) & of(x2,x4) & n_ramp(x4) & n_skateboarder(x3) & n_view(x1))
exists p1 x1 e1 s1 x2 x3 x4.((x1 = x2) & a_on(s1) & Manner(e1,s1) & without(e1,x4) & n_helmet(x4) & Actor(e1,x3) & v_skateboard(e1) & (x2 = x3) & n_person(x2))