Title
Application of entropy compression in pattern avoidance
Abstract
In combinatorics on words, a word w over an alphabet Sigma is said to avoid a pattern p over an alphabet Delta if there is no factor f of w such that f = h(p) where h : Delta* -> Sigma* is a non-erasing morphism. A pattern p is said to be k-avoidable if there exists an infinite word over a k-letter alphabet that avoids p. We give a positive answer to Problem 3.3.2 in Lothaire's book "Algebraic combinatorics on words", that is, every pattern with k variables of length at least 2(k) (resp. 3 x 2(k-1)) is 3-avoidable (resp. 2-avoidable). This conjecture was first stated by Cassaigne in his thesis in 1994. This improves previous bounds due to Bell and Goh, and Rampersad.
Year
Venue
Keywords
2013
ELECTRONIC JOURNAL OF COMBINATORICS
Word,Pattern avoidance
DocType
Volume
Issue
Journal
21.0
2.0
ISSN
Citations 
PageRank 
1077-8926
9
0.76
References 
Authors
7
2
Name
Order
Citations
PageRank
Pascal Ochem125836.91
Alexandre Pinlou216720.47