Before revision: Intuitive explanation We may write each Bi as Φ(x1...xk,y1...ym) for some x-s , which we may call "first arguments" and y-s that we may call "last arguments".
After revision: Intuitive explanation We may write each Bi as Φ(x1...xk,y1...ym) for some xs , which we may call "first arguments" and ys that we may call "last arguments".