A repairman is working on a train.
A man is making improvements on a train.
working on a train and making improvements on a train imply the same thing.
exists e1 x1 x2.(on(e1,x2) & n_train(x2) & Actor(e1,x1) & v_work(e1) & n_repairman(x1))
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_make(e1) & on(x2,x3) & n_train(x3) & n_improvement(x2) & n_man(x1))