Different people buying, and looking at different kinds of vegetables and flowers.
People buying roses and mixed vegetables.
Not all flowers are roses. Just because there are different kinds of vegetables doesn't necessarily indicate that they are mixed.
exists e1 e2 x1 x2 x3 x4 x5 x6 x7 x8.(n_kind(x6) & at(e2,x4) & subset_of(x8,x4) & n_flower(x8) & subset_of(x5,x4) & of(x5,x7) & n_vegetable(x7) & -(x5 = x6) & n_kind(x5) & Actor(e2,x3) & v_look(e2) & -(x3 = x1) & n_people(x1) & n_people(x3) & Actor(e1,x1) & v_buy(e1) & -(x1 = x2) & n_people(x2))
exists e1 s1 x1 x2 x3 x4 x5.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_buy(e1) & subset_of(x5,x3) & n_vegetable(x5) & a_mixed(s1) & Theme(s1,x5) & subset_of(x4,x3) & n_rose(x4) & (x1 = x2) & n_people(x1))