People gathering outside with signs.
people gather to play checkers at a library
People cannot be in a library and outside simultaneously.
exists e1 x1 x2 x3.(a_topic(x1) & with(e1,x3) & n_sign(x3) & r_outside(e1) & Actor(e1,x2) & v_gather(e1) & (x1 = x2) & n_people(x1))
exists e1 p1 x1.(Topic(e1,p1) & Actor(e1,x1) & v_gather(e1) & exists e2 x2 x3.(at(e2,x3) & n_library(x3) & Theme(e2,x2) & Actor(e2,x1) & v_play(e2) & n_checkers(x2)) & n_people(x1))