Chandran, Sunil L and Rajendraprasad, Deepak and Singh, Nitin
(2014)
*On Additive Combinatorics of Permutations of Z(n).*
In: DISCRETE MATHEMATICS AND THEORETICAL COMPUTER SCIENCE, 16
(2).
pp. 35-40.

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## Abstract

Let Z(n) denote the ring of integers modulo n. A permutation of Z(n) is a sequence of n distinct elements of Z(n). Addition and subtraction of two permutations is defined element-wise. In this paper we consider two extremal problems on permutations of Z(n), namely, the maximum size of a collection of permutations such that the sum of any two distinct permutations in the collection is again a permutation, and the maximum size of a collection of permutations such that no sum of two distinct permutations in the collection is a permutation. Let the sizes be denoted by s (n) and t (n) respectively. The case when n is even is trivial in both the cases, with s (n) = 1 and t (n) = n!. For n odd, we prove (n phi(n))/2(k) <= s(n) <= n!.2(-)(n-1)/2/((n-1)/2)! and 2 (n-1)/2 . (n-1/2)! <= t (n) <= 2(k) . (n-1)!/phi(n), where k is the number of distinct prime divisors of n and phi is the Euler's totient function.

Item Type: | Journal Article |
---|---|

Publication: | DISCRETE MATHEMATICS AND THEORETICAL COMPUTER SCIENCE |

Publisher: | DISCRETE MATHEMATICS THEORETICAL COMPUTER SCIENCE |

Additional Information: | Copy right for this article belongs to the DISCRETE MATHEMATICS THEORETICAL COMPUTER SCIENCE, 62 RUE DU CARDINAL MATHIEU, F-54000 NANCY, FRANCE. |

Keywords: | sums of permutations; orthomorphisms; reverse free families |

Department/Centre: | Division of Electrical Sciences > Computer Science & Automation Division of Physical & Mathematical Sciences > Mathematics |

Date Deposited: | 08 Nov 2014 05:32 |

Last Modified: | 08 Nov 2014 05:32 |

URI: | http://eprints.iisc.ac.in/id/eprint/50207 |

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