A man in a helmet is riding a bike.
A man riding a bike down a street.
A man can be riding his bike anywhere doesn't have to be down a street.
exists e1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_ride(e1) & n_bike(x3) & in(x1,x2) & n_helmet(x2) & n_man(x1))
exists e1 x1 x2 x3 x4.(a_topic(x1) & down(x1,x4) & n_street(x4) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_bike(x3) & (x1 = x2) & n_man(x1))