A group of bicyclists are all riding their bikes in a line on the street.
The bicyclists are wearing helmets.
All  bicyclists need not wear helmets
exists e1 s1 x1 x2 x3 x4 x5.(n_street(x5) & a_all(s1) & Manner(e1,s1) & in(e1,x4) & on(x4,x5) & n_line(x4) & Theme(e1,x3) & Actor(e1,x1) & v_ride(e1) & n_bike(x3) & of(x3,x1) & n_thing(x1) & of(x1,x2) & n_bicyclist(x2) & n_group(x1))
exists e1 x1 x2.(n_bicyclist(x1) & Theme(e1,x2) & Actor(e1,x1) & v_wear(e1) & n_helmet(x2))