Many people sit at a long dinner table at a formal event.
These folks are not at an informal occasion.
These folks can be part of many people and if they are at a formal event, they are not at an informal occasion.
exists e1 s1 s2 x1 x2 x3 x4.(at(e1,x4) & n_event(x4) & a_formal(s2) & Theme(s2,x4) & at(e1,x2) & n_table(x2) & of(x2,x3) & n_dinner(x3) & a_long(s1) & Theme(s1,x2) & Actor(e1,x1) & v_sit(e1) & n_people(x1) & n_quantity(x1))
exists x1.(n_folk(x1) & -exists p1 s1 x2.(at(x1,x2) & n_occasion(x2) & a_informal(s1) & Theme(s1,x2)))