A man is playing a musical instrument.
man with kids playing
A man playing would not automatically mean that he is playing a musical instrument.
exists e1 s1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_instrument(x2) & a_musical(s1) & Theme(s1,x2) & n_man(x1))
exists e1 x1 x2 x3.(a_topic(x1) & with(x1,x2) & Actor(e1,x3) & v_play(e1) & (x2 = x3) & n_kid(x2) & n_man(x1))