A group of people are on a canyon.
People are on a canyon.
People means a group
exists p1 x1 x2.(exists x3.(on(x1,x3) & n_canyon(x3)) & of(x1,x2) & n_people(x2) & n_group(x1))
exists p1 x1.(exists x2.(on(x1,x2) & n_canyon(x2)) & n_people(x1))