guy instructing people in back of train.
A man is in a train.
A guy and a man could be the same thing.  A person could be in back of a train.
exists e1 x1 x2 x3 x4 x5.(a_topic(x1) & in(e1,x4) & of(x4,x5) & n_train(x5) & n_back(x4) & Theme(e1,x3) & Actor(e1,x2) & v_instruct(e1) & n_people(x3) & (x1 = x2) & n_guy(x1))
exists p1 x1.(exists x2.(in(x1,x2) & n_train(x2)) & n_man(x1))