Use of Tree Structures for Processing Files
In data processing problems, files are frequently
used which must both be searched and altered. 
 Binary search techniques are efficient for searching
large files, but the associated file organization 
is not readily adapted to the file alterations.  Conversely,
a chained file allocation permits efficient 
alteration but cannot be searched efficiently. A file
organized into a tree-like structure is discussed, 
and it is shown that such a file may both be searched
and altered with times proportional to slog(s)N, 
where N is the number of file items and s is a parameter
of the tree.  It is also shown that optimizing 
the value of s leads to a search time which is only 25
per cent slower than the binary search.  The tree 
organization employs two data chains and may be considered
to be a compromise between the organizations 
for the binary search and the chained file.  The relation
of the tree organization to multidimensional 
indexing and to the trie structure is also discussed.
CACM May, 1963
Sussenguth Jr., E. H.
