black man painting a sign.
A man paints a protest sign.
A sign being painted doesn't have to be a protest sign.
exists e1 s1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_paint(e1) & n_sign(x3) & (x1 = x2) & n_man(x1) & a_black(s1) & Theme(s1,x1))
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_paint(e1) & n_sign(x2) & of(x2,x3) & n_protest(x3) & n_man(x1))