People are dancing at a party.
People are having fun at a party.
Both sentences mention people and a party and dancing and having fun is the same.
exists e1 x1 x2.(at(e1,x2) & n_party(x2) & Actor(e1,x1) & v_dance(e1) & n_people(x1))
exists e1 x1 x2 x3.(at(e1,x3) & n_party(x3) & Theme(e1,x2) & Actor(e1,x1) & v_have(e1) & n_fun(x2) & n_people(x1))