Length of Strings for a Merge Sort
Detailed statistics are given on the length
of maximal sorted strings which result form the 
first (internal sort) phase of a merge sort onto tapes.
 It is shown that the strings produced by an 
alternating method (i.e. one which produces ascending
and descending strings alternately) tend to be 
only three-fourths as long as those in a method which produces
only ascending strings, contrary to statements 
which have appeared previously in the literature.  A
slight modification of the read-backward polyphase 
merge algorithm is therefore suggested.
CACM November, 1963
Knuth, D. E.
