Find all functions $\displaystyle f$ defined on nonnegative integers taking nonnegative integer values such that

$\displaystyle f(f(m) + f(n)) = m + n$

for all nonnegative integers $\displaystyle m, n$.

Printable View

- Mar 1st 2009, 12:06 PMWinding FunctionFunctional Equation
Find all functions $\displaystyle f$ defined on nonnegative integers taking nonnegative integer values such that

$\displaystyle f(f(m) + f(n)) = m + n$

for all nonnegative integers $\displaystyle m, n$. - Mar 2nd 2009, 01:34 PMCaptainBlack
USA MTS 2008/9 problem, thread closed

CB