Title
Density dichotomy in random words.
Abstract
Word W is said to encounter word V provided there is a homomorphism f mapping letters to nonempty words so that phi(V) is a substring of W. For example, taking phi such that phi(h) = c and phi(u) = ien, we see that "science" encounters "huh" since cienc = phi(huh). The density of V in W, delta(V,W), is the proportion of substrings of W that are homomorphic images of V. So the density of "huh" in "science" is 2/((8)(2)). A word is doubled if every letter that appears in the word appears at least twice. The dichotomy: Let V be a word over any alphabet, Sigma a finite alphabet with at least 2 letters, and W-n is an element of Sigma(n) chosen uniformly at random. Word V is doubled if and only if E(delta(V, W-n)) -> 0 as n -> infinity. We further explore convergence for nondoubled words and concentration of the limit distribution for doubled words around its mean.
Year
Venue
Keywords
2015
CONTRIBUTIONS TO DISCRETE MATHEMATICS
Doubled words,homomorphism density,word patterns
Field
DocType
Volume
Discrete mathematics,Combinatorics,Substring,Limit distribution,Homomorphism,Mathematics,Alphabet
Journal
13
Issue
ISSN
Citations 
1
1715-0868
1
PageRank 
References 
Authors
0.51
2
2
Name
Order
Citations
PageRank
Joshua Cooper1132.56
Danny Rorabaugh211.18