Skater riding skateboard on a quarter pipe while the crowd watches.
Skater riding skateboard on a quarter pipe .
in both sentences, there is a skater riding a skateboard on a quarter pipe.
(x)
exists x1 x2 x3 x4 x5.(a_topic(x1) & on(x1,x4) & n_pipe(x4) & of(x4,x5) & n_quarter(x5) & n_skateboard(x1) & of(x1,x3) & n_riding(x3) & of(x1,x2) & n_skater(x2))