Back to Minimum overlap problem

n = 9
f(x) = 0.004837381098458996for 0x < 2/9
f(x) = 0.459493974210709653for 2/9x < 4/9
f(x) = 0.579753504802302153for 4/9x < 6/9
f(x) = 0.723007092664141244for 6/9x < 8/9
f(x) = 0.965816094448775908for 8/9x ≤ 1
f(x) = f(2-x)for 1< x ≤ 2
Illustration
α(f) < 0.382892238905007292
 maximal for 2/9 ≤ |k| ≤ 8/9