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Title: Distance matrices perturbed by Laplacians (English)
Author: Ramamurthy, Balaji
Author: Bapat, Ravindra Bhalchandra
Author: Goel, Shivani
Language: English
Journal: Applications of Mathematics
ISSN: 0862-7940 (print)
ISSN: 1572-9109 (online)
Volume: 65
Issue: 5
Year: 2020
Pages: 599-607
Summary lang: English
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Category: math
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Summary: Let $T$ be a tree with $n$ vertices. To each edge of $T$ we assign a weight which is a positive definite matrix of some fixed order, say, $s$. Let $D_{ij}$ denote the sum of all the weights lying in the path connecting the vertices $i$ and $j$ of $T$. We now say that $D_{ij}$ is the distance between $i$ and $j$. Define $D:=[D_{ij}]$, where $D_{ii}$ is the $s \times s$ null matrix and for $i \neq j$, $D_{ij}$ is the distance between $i$ and $j$. Let $G$ be an arbitrary connected weighted graph with $n$ vertices, where each weight is a positive definite matrix of order $s$. If $i$ and $j$ are adjacent, then define $L_{ij}:=-W_{ij}^{-1}$, where $W_{ij}$ is the weight of the edge $(i,j)$. Define $L_{ii}:=\sum _{i \neq j,j=1}^{n}W_{ij}^{-1}$. The Laplacian of $G$ is now the $ns \times ns$ block matrix $L:=[L_{ij}]$. In this paper, we first note that $D^{-1}-L$ is always nonsingular and then we prove that $D$ and its perturbation $(D^{-1}-L)^{-1}$ have many interesting properties in common. (English)
Keyword: tree
Keyword: Laplacian matrix
Keyword: inertia
Keyword: Haynsworth formula
MSC: 05C50
MSC: 15B48
idZBL: 07285947
idMR: MR4160783
DOI: 10.21136/AM.2020.0362-19
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Date available: 2020-09-23T13:48:25Z
Last updated: 2022-11-07
Stable URL: http://hdl.handle.net/10338.dmlcz/148367
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Reference: [1] Balaji, R., Bapat, R. B.: Block distance matrices.Electron. J. Linear Algebra 16 (2007), 435-443. Zbl 1148.15016, MR 2365897, 10.13001/1081-3810.1213
Reference: [2] Bapat, R. B.: Determinant of the distance matrix of a tree with matrix weights.Linear Algebra Appl. 416 (2006), 2-7. Zbl 1108.15006, MR 2232916, 10.1016/j.laa.2005.02.022
Reference: [3] Bapat, R., Kirkland, S. J., Neumann, M.: On distance matrices and Laplacians.Linear Algebra Appl. 401 (2005), 193-209. Zbl 1064.05097, MR 2133282, 10.1016/j.laa.2004.05.011
Reference: [4] Fiedler, M.: Matrices and Graphs in Geometry.Encyclopedia of Mathematics and Its Applications 139. Cambridge University Press, Cambridge (2011). Zbl 1225.51017, MR 2761077, 10.1017/CBO9780511973611
Reference: [5] Fiedler, M., Markham, T. L.: Completing a matrix when certain entries of its inverse are specified.Linear Algebra Appl. 74 (1986), 225-237. Zbl 0592.15002, MR 0822149, 10.1016/0024-3795(86)90125-4
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