People are gathered around for an occasion.
People are gathered around for a birthday.
Not every occasion where people are gathered around is for a birthday.
exists e1 s1 x1 x2.(for(e1,x2) & n_occasion(x2) & a_around(s1) & Manner(e1,s1) & Theme(e1,x1) & v_gather(e1) & n_people(x1))
exists e1 s1 x1 x2.(for(e1,x2) & n_birthday(x2) & a_around(s1) & Manner(e1,s1) & Theme(e1,x1) & v_gather(e1) & n_people(x1))