A man and women are on a bus.
A man and woman are riding a bus.
on a bus is a rephrasing of riding a bus
exists p1 x1 x2 x3.(exists x4.(on(x1,x4) & n_bus(x4)) & subset_of(x3,x1) & n_woman(x3) & subset_of(x2,x1) & n_man(x2))
exists e1 x1 x2 x3 x4.(Theme(e1,x4) & Actor(e1,x1) & v_ride(e1) & n_bus(x4) & n_woman(x3) & n_man(x2) & subset_of(x3,x1) & subset_of(x2,x1))