Title
Pseudopower Avoidance
Abstract
Repetition avoidance has been intensely studied since Thue's work in the early 1900's. In this paper, we consider another type of repetition, called pseudopower, inspired by the Watson-Crick complementarity property of DNA sequences. A DNA single strand can be viewed as a string over the four-letter alphabet {A,C,G, T}, wherein A is the complement of T, while C is the complement of G. Such a DNA single strand will bind to a reverse complement DNA single strand, called its Watson-Crick complement, to form a helical double-stranded DNA molecule. The Watson-Crick complement of a DNA strand is deducible from, and thus informationally equivalent to, the original strand. We use this fact to generalize the notion of the power of a word by relaxing the meaning of “sameness” to include the image through an antimorphic involution, the model of DNA Watson-Crick complementarity. Given a finite alphabet Σ, an antimorphic involution is a function &thgr; : Σ* → Σ* which is an involution, i.e., &thgr;2 equals the identity, and an antimorphism, i.e., &thgr;(uv) = &thgr;(v)&thgr;(u), for all u ∈ Σ*. For a positive integer k, we call a word w a pseudo-kth-power with respect to &thgr; if it can be written as w = u1 ... uk, where for 1 ≤ i, j ≤ k we have either ui = uj or ui = &thgr;(uj). The classical kth-power of a word is a special case of a pseudo-kth-power, where all the repeating units are identical. We first classify the alphabets Σ and the antimorphic involutions &thgr; for which there exist arbitrarily long pseudo-kth-power-free words. Then we present efficient algorithms to test whether a finite word w is pseudo-kth-power-free.
Year
DOI
Venue
2012
10.1007/978-3-642-14455-4_39
Fundam. Inform.
Keywords
Field
DocType
Watson-Crick complementarity property,DNA single strand,long pseudo-kth-power-free word,DNA sequence,antimorphic involution,helical double-stranded DNA molecule,DNA Watson-Crick complementarity,Pseudopower Avoidance,original strand,DNA strand,finite word w
Complementarity (molecular biology),Discrete mathematics,Computer science,Watson,DNA computing
Journal
Volume
Issue
ISBN
114
1
3-642-14454-3
Citations 
PageRank 
References 
1
0.58
10
Authors
3
Name
Order
Citations
PageRank
Ehsan Chiniforooshan111816.38
Lila Kari21123124.45
Zhi Xu392.61