A repairman is working on a train.
A workman is repairing the train.
Either a repairman is working or a workman is repairing.
exists e1 x1 x2.(on(e1,x2) & n_train(x2) & Actor(e1,x1) & v_work(e1) & n_repairman(x1))
exists e1 x1 x2.(n_train(x2) & Theme(e1,x2) & Actor(e1,x1) & v_repair(e1) & n_workman(x1))