A separating family is a set of subsets in which each pair of adjacent elements are found separated, each in one of two disjoint
subsets. The 26 letters of the alphabet can be separated by a family of 9,
The minimal size of the separating family for an -set is 0, 2, 3, 4, 5, 5, 6, 6, 6, 7, 7, 7, ... (OEIS A007600).
Honsberger, R. "Cai Mao-Cheng's Solution to Katona's Problem on Families of Separating Subsets." Ch. 18 in Mathematical
Gems III. Washington, DC: Math. Assoc. Amer., pp. 224-239, 1985.Sloane,
N. J. A. Sequence A007600/M0456
in "The On-Line Encyclopedia of Integer Sequences."
-set is 0, 2, 3, 4, 5, 5, 6, 6, 6, 7, 7, 7, ... (OEIS A007600).
