Issue No.06 - June (1972 vol.21)
David C. Van Voorhis , Advanced Systems Development Division, IBM Corporation, Los Gatos, Calif. 95030.
The minimum number of comparators S(N) required by an N-input sorting network is bounded below by S(N) ¿ N[log<inf>2</inf> (N) - 1] + 0(1), as a consequence of the theorem S(N) ¿ S(N - 1) + [log<inf>2</inf> (N)].
David C. Van Voorhis, "An Improved Lower Bound for Sorting Networks", IEEE Transactions on Computers, vol.21, no. 6, pp. 612-613, June 1972, doi:10.1109/TC.1972.5009021