A father and a son are crossing a busy street, near people riding bikes.
The boy is alone
If a father and son are together, neither one is alone.
exists e2 e1 s1 x1 x2 x3 x4 x5 x6 x7.(near(e1,x5) & Theme(e2,x7) & Actor(e2,x6) & v_ride(e2) & n_bike(x7) & (x5 = x6) & n_people(x5) & Theme(e1,x4) & Actor(e1,x1) & v_cross(e1) & n_street(x4) & a_busy(s1) & Theme(s1,x4) & subset_of(x3,x1) & n_son(x3) & subset_of(x2,x1) & n_father(x2))
exists s1 x1.(n_boy(x1) & Theme(s1,x1) & a_alone(s1))