A group of people waiting for the subway.
A group of people waiting for the subway and singing.
The group of people may not be singing at all.
exists e1 x1 x2 x3 x4.(n_subway(x4) & a_topic(x1) & of(x1,x2) & for(e1,x4) & Actor(e1,x3) & v_wait(e1) & (x2 = x3) & n_people(x2) & n_group(x1))
exists e1 x1 x2 x3 x4 x5 x6.(n_singing(x6) & n_subway(x5) & subset_of(x6,x4) & subset_of(x5,x4) & a_topic(x1) & of(x1,x2) & for(e1,x4) & Actor(e1,x3) & v_wait(e1) & (x2 = x3) & n_people(x2) & n_group(x1))