A group celebrates a marriage.
The group is having a big party.
When a group celebrates a marriage, it does not mean that the group is having a big party.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_celebrate(e1) & n_marriage(x2) & n_group(x1))
exists e1 s1 x1 x2.(n_group(x1) & Theme(e1,x2) & Actor(e1,x1) & v_have(e1) & n_party(x2) & a_big(s1) & Theme(s1,x2))