A boy sitting in water.
A boy sitting in a bath tub
You can not infer he is in the bath tub.
exists e1 x1 x2 x3.(a_topic(x1) & in(e1,x3) & n_water(x3) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_boy(x1))
exists e1 x1 x2 x3 x4.(a_topic(x1) & in(e1,x3) & n_tub(x3) & of(x3,x4) & n_bath(x4) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_boy(x1))