An artist is painting a portrait of a pet dog.
There is an artist painting.
An artist could be painting a portrait of a dog.
exists e1 s1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_paint(e1) & of(x2,x3) & n_dog(x3) & a_pet(s1) & Theme(s1,x3) & n_portrait(x2) & n_artist(x1))
exists p1 x1 x2 x3.((x1 = x2) & n_painting(x2) & of(x2,x3) & n_artist(x3))