Function kmf(x,y) is the minimum number of moves for a knight to move x units to the right and y units forward.

(1) Find kmf(x,y) for non-negative integer values of x and y from 0 to 7.
(2) Can you find an expression for kmf(x,y) in terms of x and y?

Notes:
Assume this is an infinite chess board so there are no edge-of-the-board boundary issues.
To avoid duplication, ignore cases where y is less than x.