A repairman is working on a train.
A mechanic is fixing a locomotive.
fixing a locomotive and working on a train are 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.(Theme(e1,x2) & Actor(e1,x1) & v_fix(e1) & n_locomotive(x2) & n_mechanic(x1))