People are walking in the street while other people sit and have lunch.
Monsters are attacking the people
People don't sit and have lunch nor would be walking if a monster was attacking people.
exists e1 p1 x1 x2 x5.(n_street(x2) & exists e2 e3 x3 x4 x6.(Theme(e3,x6) & Actor(e3,x4) & v_have(e3) & n_lunch(x6) & -(x4 = x5) & n_people(x4) & Actor(e2,x3) & v_sit(e2) & -(x3 = x1) & n_people(x3)) & n_people(x5) & n_people(x1) & n_people(x1) & while(e1,p1) & in(e1,x2) & Actor(e1,x1) & v_walk(e1))
exists e1 x1 x2.(n_people(x2) & Theme(e1,x2) & Actor(e1,x1) & v_attack(e1) & n_monster(x1))