There is a grown duck and several baby ducks.
The grown duck is the mother duck.
You can not infer one is the mother duck.
exists p1 x1 s1 s2 x2 x3 x4 x5.((x1 = x2) & subset_of(x4,x2) & n_duck(x4) & of(x4,x5) & n_baby(x5) & a_several(s2) & Theme(s2,x4) & subset_of(x3,x2) & n_duck(x3) & a_grown(s1) & Theme(s1,x3))
exists p1 s1 x1 x2.(n_duck(x1) & n_duck(x1) & of(x1,x2) & n_mother(x2) & a_grown(s1) & Theme(s1,x1) & (x1 = x1))