A group of people at a rodeo.
Some people are at a rodeo.
A group of people means there is some people at the rodeo.
exists x1 x2 x3.(a_topic(x1) & of(x1,x2) & at(x2,x3) & n_rodeo(x3) & n_people(x2) & n_group(x1))
exists p1 x1.(exists x2.(at(x1,x2) & n_rodeo(x2)) & n_people(x1))