A lot of people are standing facing their backs to the camera with hot pink signs posted on their back.
people with their backs to the camera have pink posts on their backs
People with their backs to the camera is the same thing as facing their backs to the camera.
exists e1 e3 e2 s1 x1 x2 x3 x4 x5 x6 x7.(n_camera(x4) & for(e1,e2) & to(e2,x4) & with(x4,x5) & on(e3,x3) & n_back(x3) & n_back(x3) & of(x3,x1) & n_thing(x1) & n_thing(x1) & Theme(e3,x7) & v_post(e3) & (x5 = x7) & n_sign(x5) & of(x5,x6) & n_pink(x6) & a_hot(s1) & Theme(s1,x5) & Theme(e2,x3) & Actor(e2,x1) & v_face(e2) & Actor(e1,x1) & v_stand(e1) & of(x1,x2) & n_people(x2) & n_lot(x1))
exists e1 s1 x1 x2 x3 x4.(n_camera(x3) & Theme(e1,x4) & Actor(e1,x1) & v_have(e1) & on(x4,x2) & n_back(x2) & n_back(x2) & of(x2,x1) & n_thing(x1) & n_thing(x1) & n_post(x4) & a_pink(s1) & Theme(s1,x4) & to(x1,x3) & with(x1,x2) & n_people(x1))