A Discrete Nodal Domain Theorem for Trees

Türker Biyikoglu

Publication: Working/Discussion PaperWU Working Paper

Abstract

Let G be a connected graph with n vertices and let x=(x1, ..., xn) be a real vector. A positive (negative) sign graph of the vector x is a maximal connected subgraph of G on vertices xi>0 (xi<0). For an eigenvalue of a generalized Laplacian of a tree: We characterize the maximal number of sign graphs of an eigenvector. We give an O(n2) time algorithm to find an eigenvector with maximum number of sign graphs and we show that finding an eigenvector with minimum number of sign graphs is an NP-complete problem. (author's abstract)
Original languageEnglish
Place of PublicationVienna
PublisherDepartment of Statistics and Mathematics, Abt. f. Angewandte Statistik u. Datenverarbeitung, WU Vienna University of Economics and Business
Publication statusPublished - 2002

Publication series

NamePreprint Series / Department of Applied Statistics and Data Processing
No.43

WU Working Paper Series

  • Preprint Series / Department of Applied Statistics and Data Processing

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