The man is showing his artwork at the park.
The artwork is of nature
Artwork is not necessarily of nature.
exists e1 x1 x2 x3.(n_park(x3) & n_artwork(x2) & of(x2,x1) & n_male(x1) & n_man(x1) & at(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_show(e1))
exists p1 x1.(n_artwork(x1) & exists x2.(of(x1,x2) & n_nature(x2)))