Two people signing books.
Two people are at a library book signing event.
Two people are signing books it dose not mean they are at a signing event.
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_sign(e1) & n_book(x3) & (x1 = x2) & n_people(x1) & card_eq_2(x1))
exists p1 x1.(exists x2 x3 x4 x5.(at(x1,x2) & n_event(x2) & of(x2,x5) & n_signing(x5) & of(x2,x4) & n_book(x4) & of(x2,x3) & n_library(x3)) & n_people(x1) & card_eq_2(x1))