A white sign with a blue arrow instructs people where to go.
A white sign with the blue arrow is in the train station.
A white sign with a blue arrow  can be anywhere not particularly in a train station.
exists e1 s1 s2 x1 x2 x3 x4 x5.(for(x2,x1) & with(x2,x3) & Theme(e1,x5) & Actor(e1,x4) & v_instruct(e1) & n_people(x5) & (x3 = x4) & n_arrow(x3) & a_blue(s2) & Theme(s2,x3) & n_manner(x2) & exists e2 x6.(Actor(e2,x6) & v_go(e2)) & n_sign(x1) & a_white(s1) & Theme(s1,x1))
exists p1 s1 s2 x1 x2 x3 x4.(n_station(x3) & of(x3,x4) & n_train(x4) & n_arrow(x2) & a_blue(s2) & Theme(s2,x2) & in(x1,x3) & with(x1,x2) & n_sign(x1) & a_white(s1) & Theme(s1,x1))