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, ... (Sloane's A007600).

**References**

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 ``An On-Line Version of the Encyclopedia of Integer Sequences.''
http://www.research.att.com/~njas/sequences/eisonline.html and Sloane, N. J. A. and Plouffe, S.
*The Encyclopedia of Integer Sequences.* San Diego: Academic Press, 1995.

© 1996-9

1999-05-26