On Unavoidable Sets of Word Patterns.

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Bibliographic Details
Title: On Unavoidable Sets of Word Patterns.
Authors: Burstein, Alexander1 burstein@orion.math.iastate.edu, Kitaev, Sergey2 kitaev@ms.uky.edu
Source: SIAM Journal on Discrete Mathematics. 2005, Vol. 19 Issue 2, p371. 11p. 3 Diagrams, 1 Chart.
Subjects: Programming languages, Character sets (Data processing), Alphabet -- Data processing, Möbius function, Mathematical programming, Computer programming, Computational mathematics
Abstract: We introduce the notion of unavoidable (complete) sets of word patterns, which is a refinement for that of words, and study certain numerical characteristics for unavoidable sets of patterns. In some cases we employ the graph of pattern overlaps introduced in this paper, which is a subgraph of the de Bruijn graph and which we prove to be Hamiltonian. In other cases we reduce a problem under consideration to known facts on unavoidable sets of words. We also give a relation between our problem and the extensively studied universal cycles and prove that there exists a universal cycle for word patterns of any length over any alphabet. The Stirling numbers of the second kind and the Mobius function appear in our results. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:We introduce the notion of unavoidable (complete) sets of word patterns, which is a refinement for that of words, and study certain numerical characteristics for unavoidable sets of patterns. In some cases we employ the graph of pattern overlaps introduced in this paper, which is a subgraph of the de Bruijn graph and which we prove to be Hamiltonian. In other cases we reduce a problem under consideration to known facts on unavoidable sets of words. We also give a relation between our problem and the extensively studied universal cycles and prove that there exists a universal cycle for word patterns of any length over any alphabet. The Stirling numbers of the second kind and the Mobius function appear in our results. [ABSTRACT FROM AUTHOR]
ISSN:08954801
DOI:10.1137/S0895480104445678