There is a man sitting in a restaurant at night.
There is a man at a restaurant.
A man sitting in a restaurant at night also implies that there is a man at a restaurant.
exists p1 x1 e1 x2 x3 x4 x5.((x1 = x2) & at(e1,x5) & n_night(x5) & in(e1,x4) & n_restaurant(x4) & Actor(e1,x3) & v_sit(e1) & (x2 = x3) & n_man(x2))
exists p1 x1 x2 x3.((x1 = x2) & at(x2,x3) & n_restaurant(x3) & n_man(x2))