A group of girls sit back to back.
Girls leaning against each others backs.
The girls could be supporting themselves and not be relying or leaning on each other
exists e1 s1 x1 x2 x3.(Theme(e1,s1) & Theme(s1,x3) & a_back(s1) & r_back(e1) & Actor(e1,x1) & v_sit(e1) & of(x1,x2) & n_girl(x2) & n_group(x1))
exists e1 x1.(n_person(x1) & ne_nam_girls(x1) & all x2.((-(x2 = x1) & n_person(x2)) -> exists x3.(against(e1,x2) & Time(x2,x3) & n_back(x3))) & Actor(e1,x1) & v_lean(e1))