function AP(x,y: integer) returns integer;
if x = 0 then return y+1
else if y = 0 then return AP(x-1,1)
else return AP(x-1, AP(x,y-1))
(a) Show that on all nonnegative arguments x and y, the function AP terminates.
(b) Show that for any x, AP(x, y) > y.
