A group of people wearing helmets and riding on bikes.
There is only one person riding a bike.
If only one person is riding, then there cannot be a group.
exists e2 e1 x1 x2 x3 x4 x5 x6.(a_topic(x1) & on(e2,x6) & n_bike(x6) & Actor(e2,x5) & v_ride(e2) & (x1 = x5) & Theme(e1,x4) & Actor(e1,x3) & v_wear(e1) & n_helmet(x4) & (x1 = x3) & of(x1,x2) & n_people(x2) & n_group(x1))
exists p1 x1 e1 x2 x3 x4.((x1 = x2) & Theme(e1,x4) & Actor(e1,x3) & v_ride(e1) & n_bike(x4) & (x2 = x3) & n_person(x2) & card_eq_1(x2) & r_only(x2))