A man with a black shirt watching a baby.
A man watches a baby.
A man with a black shirt watching a baby is just a longer description of a man watches a baby.
exists e1 s1 x1 x2 x3 x4.(a_topic(x1) & with(x1,x2) & Theme(e1,x4) & Actor(e1,x3) & v_watch(e1) & n_baby(x4) & (x2 = x3) & n_shirt(x2) & a_black(s1) & Theme(s1,x2) & n_man(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_watch(e1) & n_baby(x2) & n_man(x1))