Counting Non-Isomorphic Maximal Independent Sets of the n-Cycle Graph
Raymond Bisdorff
Computer Science and Communications Research Unit
University of Luxembourg
162A, avenue de la Faïencerie
L-1511 Luxembourg
Luxembourg
Jean-Luc Marichal
Mathematics Research Unit
University of Luxembourg
162A, avenue de la Faïencerie
L-1511 Luxembourg
Luxembourg
Abstract:
The number of maximal independent sets of the n-cycle graph
Cn is
known to be the nth term of the Perrin sequence. The action of the
automorphism group of Cn
on the family of these maximal independent
sets partitions this family into disjoint orbits, which represent the
non-isomorphic (i.e., defined up to a rotation and a reflection)
maximal independent sets. We provide exact formulas for the total
number of orbits and the number of orbits having a given number of
isomorphic representatives. We also provide exact formulas for the
total number of unlabeled (i.e., defined up to a rotation) maximal
independent sets and the number of unlabeled maximal independent sets
having a given number of isomorphic representatives. It turns out that
these formulas involve both the Perrin and Padovan sequences.
Full version: pdf,
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(Concerned with sequences
A000010
A000931
A001608
A008683
A113788
A127682
A127683
A127684
A127685
A127686
A127687
.)
Received May 26 2008;
revised version received November 25 2008.
Published in Journal of Integer Sequences, December 14 2008.
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