A bunch of little boys in bathing trunks running.
A group of young children run in their swim attire.
A bunch of little boys is a group of young children.  Bathing trunks is swim attire.
exists e1 e2 s1 x1 x2 x3 x4 x5.(a_topic(x1) & Theme(e2,x4) & Actor(e2,x3) & v_bath(e2) & Actor(e1,x5) & v_run(e1) & (x4 = x5) & n_trunk(x4) & (x1 = x3) & of(x1,x2) & n_boy(x2) & a_little(s1) & Theme(s1,x2) & n_bunch(x1))
exists e1 s1 x1 x2 x3 x4.(in(e1,x3) & n_attire(x3) & of(x3,x4) & n_swim(x4) & of(x3,x1) & n_thing(x1) & Actor(e1,x1) & v_run(e1) & of(x1,x2) & n_child(x2) & a_young(s1) & Theme(s1,x2) & n_group(x1))