Grandma is introducing her granddaughter, the cellist.
The two women are at a concert.
The grandma and the granddaughter  is not said to be at a concert.
exists e1 x1 x2 x3 x4.(n_cellist(x4) & n_granddaughter(x3) & of(x3,x1) & n_female(x1) & ne_geo_grandma(x1) & Theme(e1,x2) & Actor(e1,x1) & v_introduce(e1) & subset_of(x4,x2) & subset_of(x3,x2))
exists p1 x1.(n_woman(x1) & card_eq_2(x1) & exists x2.(at(x1,x2) & n_concert(x2)))