A gang of bikers sit in traffic.
a group of men are on bikes
A gang is the same as a group. The only way bikers can sit in traffic is if they are on bikes.
exists e1 x1 x2 x3.(in(e1,x3) & n_traffic(x3) & Actor(e1,x1) & v_sit(e1) & of(x1,x2) & n_biker(x2) & n_gang(x1))
exists p1 x1 x2.(exists x3.(on(x1,x3) & n_bike(x3)) & of(x1,x2) & n_man(x2) & n_group(x1))