The Kraft inequality states that the lengths 
of the codewords of
a 
-ary
prefix-free code, where 
, satisfy
 |
Conversely, every finite or countable sequence of positive integer lengths satisfying this inequality
is the sequence of lengths of some 
-ary prefix-free code. The inequality follows by associating
codewords with disjoint cylinders in the infinite 
-ary tree.
