{ "id": "1810.01210", "version": "v1", "published": "2018-10-02T12:49:32.000Z", "updated": "2018-10-02T12:49:32.000Z", "title": "On non-repetitive sequences of arithmetic progressions:the cases $k \\in \\{4,5,6,7,8\\}$", "authors": [ "Borut Lužar", "Martina Mockovčiaková", "Pascal Ochem", "Alexandre Pinlou", "Roman Soták" ], "categories": [ "math.CO" ], "abstract": "A $d$-subsequence of a sequence $\\varphi = x_1\\dots x_n$ is a subsequence $x_i x_{i+d} x_{i+2d} \\dots$, for any positive integer $d$ and any $i$, $1 \\le i \\le n$. A \\textit{$k$-Thue sequence} is a sequence in which every $d$-subsequence, for $1 \\le d \\le k$, is non-repetitive, i.e. it contains no consecutive equal subsequences. In 2002, Grytczuk proposed a conjecture that for any $k$, $k+2$ symbols are enough to construct a $k$-Thue sequences of arbitrary lengths. So far, the conjecture has been confirmed for $k \\in \\{1,2,3,5\\}$. Here, we present two different proving techniques, and confirm it for all $k$, with $2 \\le k \\le 8$.", "revisions": [ { "version": "v1", "updated": "2018-10-02T12:49:32.000Z" } ], "analyses": { "subjects": [ "68R15" ], "keywords": [ "arithmetic progressions", "non-repetitive sequences", "thue sequence", "conjecture", "consecutive equal subsequences" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }