9.2-1

Show that RANDOMIZED-SELECT never makes a recursive call to a 0-length array.
RANDOMIZED-SELECT has two recursive calls for i < k and i >k. If i > k the values q is reduced by (q = q-1 see the method argument). If we assume i > k is called in every recursive call the q is decreased by 1 every time. The base case will return when p = q . The least values q can take is p when (q=p) we have 1-length array. So the recursion returns for 1-length array.