Question

Construct a function f : R

2 ¡æ R such that its saddle points are given by {(n, 2m+1−n)|n ¡ô
Z, m ¡ô Z}, where Z is the set of integers.

Answer 1

google is your friend. You might want to start here:

http://math.stackexchange.com/questions/1942079/constructing-a-function-with-saddle-points