A group of men gather and play instruments.
A rock band is playing.
Just because some men play instruments does not mean they are a rock band.
exists e1 e2 x1 x2 x3 x4 x5 x6.(Theme(e2,x6) & Actor(e2,x4) & v_play(e2) & n_instrument(x6) & of(x4,x5) & n_man(x5) & n_group(x4) & Theme(e1,x3) & Actor(e1,x1) & v_gather(e1) & n_instrument(x3) & of(x1,x2) & n_man(x2) & n_group(x1))
exists e1 x1 x2.(Actor(e1,x1) & v_play(e1) & n_band(x1) & of(x1,x2) & n_rock(x2))