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On k-abelian palindromes

Published: 01 June 2018 Publication History

Abstract

A word is called a palindrome if it is equal to its reversal. In the paper we consider a k-abelian modification of this notion. Two words are called k-abelian equivalent if they contain the same number of occurrences of each factor of length at most k. We say that a word is a k-abelian palindrome if it is k-abelian equivalent to its reversal. A question we deal with is the following: how many distinct palindromes can a word contain? It is well known that a word of length n can contain at most n+1 distinct palindromes as its factors; such words are called rich. On the other hand, there exist infinite words containing only finitely many distinct palindromes as their factors; such words are called poor. We show that in the k-abelian case there exist infinite words containing finitely many distinct k-abelian palindromic factors. For rich words we show that there exist finite words of length n containing (n2) distinct k-abelian palindromes as their factors.

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Published In

cover image Information and Computation
Information and Computation  Volume 260, Issue C
June 2018
134 pages

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Academic Press, Inc.

United States

Publication History

Published: 01 June 2018

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  1. Infinite words
  2. Palindromes
  3. Rich words
  4. k-Abelian equivalence

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