Artist painting on a canvas.
A person is painting.
An artist painting is the same as a person is painting.
exists s1 x1 x2.(a_topic(x1) & on(x1,x2) & n_canvas(x2) & n_painting(x1) & a_artist(s1) & Theme(s1,x1))
exists p1 x1.(exists x2.((x1 = x2) & n_painting(x2)) & n_person(x1))