A group of children are playing brass instruments.
A string quartet plays for the President.
Brass instruments are not found in a string quartet.
exists e1 x1 x2 x3 x4.(Theme(e1,x3) & Actor(e1,x1) & v_play(e1) & n_instrument(x3) & of(x3,x4) & n_brass(x4) & of(x1,x2) & n_child(x2) & n_group(x1))
exists e1 x1 x2 x3.(ne_nam_president(x3) & for(e1,x3) & Actor(e1,x1) & v_play(e1) & n_quartet(x1) & of(x1,x2) & n_string(x2))