"Permutational labeling of constant weight Gray codes." by Inessa Levi
 

Authors

Inessa Levi

Document Type

Article

Publication Date

2002

Publication Title

Cambridge University Press

Abstract

We prove that for positive integers n and r satisfying 1 < r < n, with the single exception of n = 4 and r = 2, there exists a constant weight Gray code of r-sets of Xn = {1,2,... ,n} that admits an orthogonal labelling by distinct partitions, with each subsequent partition obtained from the previous one by an application of a permutation of the underlying set. Specifically, an r-set A and a partition •K of Xn are said to be orthogonal if every class of n meets A in exactly one element. We prove that for all n and r as stated, and i = 1,2,..., I J taken modulo [ J, there exists a list Ai, A2,..., A(n\ of the distinct r-sets of Xn with \A\ n Aj+1| = r - 1 and a list of distinct partitions TTI, 7T2,..., irin\ such that TTJ is orthogonal to both Ai and Ai+i, and 7Tj+i = TTiAj for a suitable permutation A* of Xn.

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