Several people are riding motorcycles down a narrow street.
A bunch of bikers riding min motorcycles down a narrow street.
It can't be assumed that all people who ride motorcycles are riding min motorcycles
exists e1 s1 s2 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & down(x2,x3) & n_street(x3) & a_narrow(s2) & Theme(s2,x3) & n_motorcycle(x2) & n_people(x1) & a_several(s1) & Theme(s1,x1))
exists e1 s1 s2 x1 x2 x3 x4 x5.(a_topic(x1) & Theme(e1,x4) & Actor(e1,x3) & v_ride(e1) & down(x4,x5) & n_street(x5) & a_narrow(s2) & Theme(s2,x5) & n_motorcycle(x4) & a_min(s1) & Theme(s1,x4) & (x1 = x3) & of(x1,x2) & n_biker(x2) & n_bunch(x1))