A woman reading a book while riding a train.
A woman is reading on a train on her  way home from work.
A woman reading on a train does not tell you where she is going. Sentence 2 makes it clear that she is on her way home from work.
exists e2 e1 x1 x2 x3 x4.(a_topic(x1) & while(e1,e2) & Theme(e2,x4) & Actor(e2,x2) & v_ride(e2) & n_train(x4) & Theme(e1,x3) & Actor(e1,x2) & v_read(e1) & n_book(x3) & (x1 = x2) & n_woman(x1))
exists e1 x1 x2 x3 x4 x5.(on(e1,x2) & on(x2,x3) & from(x3,x5) & n_work(x5) & n_home(x3) & of(x3,x4) & n_way(x4) & of(x3,x1) & n_female(x1) & n_train(x2) & Actor(e1,x1) & v_read(e1) & n_woman(x1))