Variations of the Morse-Hedlund theorem for k-abelian equivalence
In this paper we investigate local-to-global phenomena for a new family of complexity functions of infinite words indexed by k ≥ 0. Two finite words u and v are said to be k-abelian equivalent if for all words x of length less than or equal to k, the number of occurrences of x in u is equal to the n...
Elmentve itt :
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| Dokumentumtípus: | Cikk |
| Megjelent: |
2017
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| Sorozat: | Acta cybernetica
23 No. 1 |
| Kulcsszavak: | Matematika |
| Tárgyszavak: | |
| doi: | 10.14232/actacyb.23.1.2017.11 |
| Online Access: | http://acta.bibl.u-szeged.hu/50069 |
| Tartalmi kivonat: | In this paper we investigate local-to-global phenomena for a new family of complexity functions of infinite words indexed by k ≥ 0. Two finite words u and v are said to be k-abelian equivalent if for all words x of length less than or equal to k, the number of occurrences of x in u is equal to the number of occurrences of x in v. This defines a family of equivalence relations, bridging the gap between the usual notion of abelian equivalence (when k = 1) and equality (when k = ∞). Given an infinite word w, we consider the associated complexity function which counts the number of k-abelian equivalence classes of factors of w of length n. As a whole, these complexity functions have a number of common features: each gives a characterization of periodicity in the context of bi-infinite words, and each can be used to characterize Sturmian words in the framework of aperiodic one-sided infinite words. Nevertheless, they also exhibit a number of striking differences, the study of which is one of the main topics of our paper. |
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| Terjedelem/Fizikai jellemzők: | 175-189 |
| ISSN: | 0324-721X |