“…comparisons are necessary (see Knuth [5]). However, better lower bounds are obtained: Wells [8] obtained the greater lower bound for 12 elements, Kasai et al [4] for 13 elements, and Peczarski [6,7] for 14, 15, and 22 elements, by exhaustive computations. Ford-Johnson algorithm [2] gives upper bounds for the minimum number of comparisons.…”