The Content of the Index: Separators Instead of Keys
The index serves as a kind of road map for for the sequence set ==> We do not need to have keys in the index set.
What we really need are separators capable of distinguishing between two blocks.
We can save space by using variable-length separators and placing the shortest separator in the index structure.
Rules are: Key < separator ==> Go left . Key = separator ==> Go right . Key > separator ==> Go right