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A periodicity property of iterated morphisms

Juha Honkala (2007)

RAIRO - Theoretical Informatics and Applications

Suppose ƒ : X* → X* is a morphism and u,v ∈ X*. For every nonnegative integer n, let zn be the longest common prefix of ƒn(u) and ƒn(v), and let un,vn ∈ X* be words such that ƒn(u) = znun and ƒn(v) = znvn. We prove that there is a positive integer q such that for any positive integer p, the prefixes of un (resp. vn) of length p form an ultimately periodic sequence having period q. Further, there is a value of q which works for all words u,v ∈ X*.

A sparse dynamic programming algorithm for alignment with non-overlapping inversions

Alair Pereira Do Lago, Ilya Muchnik, Casimir Kulikowski (2005)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

Alignment of sequences is widely used for biological sequence comparisons, and only biological events like mutations, insertions and deletions are considered. Other biological events like inversions are not automatically detected by the usual alignment algorithms, thus some alternative approaches have been tried in order to include inversions or other kinds of rearrangements. Despite many important results in the last decade, the complexity of the problem of alignment with inversions is still unknown....

A sparse dynamic programming algorithm for alignment with non-overlapping inversions

Alair Pereira do Lago, Ilya Muchnik, Casimir Kulikowski (2010)

RAIRO - Theoretical Informatics and Applications

Alignment of sequences is widely used for biological sequence comparisons, and only biological events like mutations, insertions and deletions are considered. Other biological events like inversions are not automatically detected by the usual alignment algorithms, thus some alternative approaches have been tried in order to include inversions or other kinds of rearrangements. Despite many important results in the last decade, the complexity of the problem of alignment with inversions is...

A test-set for k -power-free binary morphisms

F. Wlazinski (2001)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

A morphism f is k -power-free if and only if f ( w ) is k -power-free whenever w is a k -power-free word. A morphism f is k -power-free up to m if and only if f ( w ) is k -power-free whenever w is a k -power-free word of length at most m . Given an integer k 2 , we prove that a binary morphism is k -power-free if and only if it is k -power-free up to k 2 . This bound becomes linear for primitive morphisms: a binary primitive morphism is k -power-free if and only if it is k -power-free up to 2 k + 1

A test-set for k-power-free binary morphisms

F. Wlazinski (2010)

RAIRO - Theoretical Informatics and Applications

A morphism f is k-power-free if and only if f(w) is k-power-free whenever w is a k-power-free word. A morphism f is k-power-free up to m if and only if f(w) is k-power-free whenever w is a k-power-free word of length at most m. Given an integer k ≥ 2, we prove that a binary morphism is k-power-free if and only if it is k-power-free up to k2. This bound becomes linear for primitive morphisms: a binary primitive morphism is k-power-free if and only if it is k-power-free up to 2k+1

Currently displaying 61 – 80 of 893