Research output: Contribution to journal › Article › peer-review
K-Abelian equivalence and rationality. / Cassaigne, Julien; Karhumäki, Juhani; Puzynina, Svetlana; Whiteland, Markus A.
In: Fundamenta Informaticae, Vol. 154, No. 1-4, 01.01.2017, p. 65-94.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - K-Abelian equivalence and rationality
AU - Cassaigne, Julien
AU - Karhumäki, Juhani
AU - Puzynina, Svetlana
AU - Whiteland, Markus A.
PY - 2017/1/1
Y1 - 2017/1/1
N2 - Two words u and v are said to be k-abelian equivalent if, for each word x of length at most k, the number of occurrences of x as a factor of u is the same as for v. We study some combinatorial properties of k-abelian equivalence classes. Our starting point is a characterization of k-abelian equivalence by rewriting, so-called k-switching. Using this characterization we show that, over any fixed alphabet, the language of lexicographically least representatives of k-abelian equivalence classes is a regular language. From this we infer that the sequence of the numbers of equivalence classes is -rational. Furthermore, we show that the above sequence is asymptotically equal to a certain polynomial depending on k and the alphabet size.
AB - Two words u and v are said to be k-abelian equivalent if, for each word x of length at most k, the number of occurrences of x as a factor of u is the same as for v. We study some combinatorial properties of k-abelian equivalence classes. Our starting point is a characterization of k-abelian equivalence by rewriting, so-called k-switching. Using this characterization we show that, over any fixed alphabet, the language of lexicographically least representatives of k-abelian equivalence classes is a regular language. From this we infer that the sequence of the numbers of equivalence classes is -rational. Furthermore, we show that the above sequence is asymptotically equal to a certain polynomial depending on k and the alphabet size.
KW - k-abelian equivalence
KW - Rational sequences
KW - Regular languages
UR - http://www.scopus.com/inward/record.url?scp=85027340559&partnerID=8YFLogxK
U2 - 10.3233/FI-2017-1553
DO - 10.3233/FI-2017-1553
M3 - Article
AN - SCOPUS:85027340559
VL - 154
SP - 65
EP - 94
JO - Fundamenta Informaticae
JF - Fundamenta Informaticae
SN - 0169-2968
IS - 1-4
ER -
ID: 35281155