A security guard on watch duty at the museum.
The security guard is protecting artwork.
Just because the security guard is on watch doesn't imply he is protecting artwork.
exists x1 x2 x3 x4 x5.(n_museum(x5) & a_topic(x1) & on(x1,x3) & at(x3,x5) & n_duty(x3) & of(x3,x4) & n_watch(x4) & n_guard(x1) & of(x1,x2) & n_security(x2))
exists e1 x1 x2 x3.(n_guard(x1) & of(x1,x2) & n_security(x2) & Theme(e1,x3) & Actor(e1,x1) & v_protect(e1) & n_artwork(x3))