Kraft-McMilan Inequality defines the limit of the code word lengths of in a #prefix code.
$$ K = \sum^{n}_{i=1} r^{-l_i} \le 1 $$
Where:
- \(n\) is the size of the source alphabet \(s_k\)
- \(r\) is the encoding form (usually in binary)
- \(l\) is the length of the code word
It is a necessary condition# for a prefix code to be constructable.