People standing in front of mechanical equipment.
People lay in front of mechanical machines.
The people can only be either standing in front of mechanical equipment, or they lay in front of the mechanical equipment.
exists e1 s1 x1 x2 x3 x4.(a_topic(x1) & in(e1,x3) & of(x3,x4) & n_equipment(x4) & a_mechanical(s1) & Theme(s1,x4) & n_front(x3) & Actor(e1,x2) & v_stand(e1) & (x1 = x2) & n_people(x1))
exists e1 s1 x1 x2 x3.(in(e1,x2) & of(x2,x3) & n_machine(x3) & a_mechanical(s1) & Theme(s1,x3) & n_front(x2) & Actor(e1,x1) & v_lay(e1) & n_people(x1))