These young people are relaxing on the grass.
These young people are having a picnic
It cannot be inferred that the people relaxing on the grass are having a picnic.
exists e1 s1 x1 x2.(n_grass(x2) & n_people(x1) & a_young(s1) & Theme(s1,x1) & on(e1,x2) & Actor(e1,x1) & v_relax(e1))
exists e1 s1 x1 x2.(n_people(x1) & a_young(s1) & Theme(s1,x1) & Theme(e1,x2) & Actor(e1,x1) & v_have(e1) & n_picnic(x2))