A girl getting dressing in erotica.
A girl is in her underwear.
Just because a girl is dressing in erotica does not necessarily mean that she is in her underwear.  Many erotica outfits do not include underwear.
exists e1 x1 x2 x3 x4.(a_topic(x1) & in(e1,x4) & n_erotica(x4) & Theme(e1,x3) & Actor(e1,x2) & v_get(e1) & n_dressing(x3) & (x1 = x2) & n_girl(x1))
exists p1 x1 x2.(in(x1,x2) & n_underwear(x2) & of(x2,x1) & n_female(x1) & n_girl(x1))