A lot of people are in a exercise class, riding bikes.
The people are running on treadmills.
One cannot be riding bikes and running on treadmills at the same time.
exists e1 p1 x1 x2 x3.(for(p1,e1) & Theme(e1,x3) & Actor(e1,x1) & v_ride(e1) & n_bike(x3) & exists x4 x5.(in(x1,x4) & n_class(x4) & of(x4,x5) & n_exercise(x5)) & of(x1,x2) & n_people(x2) & n_lot(x1))
exists e1 x1 x2.(n_people(x1) & on(e1,x2) & n_treadmill(x2) & Actor(e1,x1) & v_run(e1))