A young boy sits while eating.
A boy is eating dinner.
The fact that a boy is eating a sandwich doesn't imply he is eating dinner.
exists e1 e2 s1 x1.(while(e1,e2) & Actor(e2,x1) & v_eat(e2) & Actor(e1,x1) & v_sit(e1) & n_boy(x1) & a_young(s1) & Theme(s1,x1))
exists p1 x1.(exists s1 x2.((x1 = x2) & n_dinner(x2) & a_eating(s1) & Theme(s1,x2)) & n_boy(x1))