A repairman is working on a train.
Some people repairing the train.
It cannot be inferred that there are multiple people repairing the train.
exists e1 x1 x2.(on(e1,x2) & n_train(x2) & Actor(e1,x1) & v_work(e1) & n_repairman(x1))
exists e1 x1 x2 x3.(n_train(x3) & a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_repair(e1) & (x1 = x2) & n_people(x1))