NOTE ON THE SPANNING TREES AND COTREES OF A CONNECTED GRAPH

1984 ◽  
Vol 17 (3) ◽  
Author(s):  
Dänut Marcu
10.37236/5295 ◽  
2016 ◽  
Vol 23 (1) ◽  
Author(s):  
Jiang Zhou ◽  
Zhongyu Wang ◽  
Changjiang Bu

Let $G$ be a connected graph of order $n$. The resistance matrix of $G$ is defined as $R_G=(r_{ij}(G))_{n\times n}$, where $r_{ij}(G)$ is the resistance distance between two vertices $i$ and $j$ in $G$. Eigenvalues of $R_G$ are called R-eigenvalues of $G$. If all row sums of $R_G$ are equal, then $G$ is called resistance-regular. For any connected graph $G$, we show that $R_G$ determines the structure of $G$ up to isomorphism. Moreover, the structure of $G$ or the number of spanning trees of $G$ is determined by partial entries of $R_G$ under certain conditions. We give some characterizations of resistance-regular graphs and graphs with few distinct R-eigenvalues. For a connected regular graph $G$ with diameter at least $2$, we show that $G$ is strongly regular if and only if there exist $c_1,c_2$ such that $r_{ij}(G)=c_1$ for any adjacent vertices $i,j\in V(G)$, and $r_{ij}(G)=c_2$ for any non-adjacent vertices $i,j\in V(G)$.


2018 ◽  
Vol 5 (3) ◽  
pp. 265-281 ◽  
Author(s):  
Maumita Chakraborty ◽  
Sumon Chowdhury ◽  
Joymallya Chakraborty ◽  
Ranjan Mehera ◽  
Rajat Kumar Pal

1991 ◽  
Vol 01 (02) ◽  
pp. 99-107 ◽  
Author(s):  
JEFFERY S. SALOWE

Given a connected graph G=(V,E) with positive edge weights, define the distance dG(u,v) between vertices u and v to be the length of a shortest path from u to v in G. A spanning subgraph G' of G is said to be a t-spanner for G if, for every pair of vertices u and v, dG'(u,v)≤t·dG(u,v). Consider a complete graph G whose vertex set is a set of n points in [Formula: see text] and whose edge weights are given by the Lp distance between respective points. Given input parameter ∊, 0<∊≤1, we show how to construct a (1+∊)-spanner for G containing [Formula: see text] edges in [Formula: see text] time. We apply this spanner to the construction of approximate minimum spanning trees.


2020 ◽  
Vol 66 (2) ◽  
pp. 1248-1260
Author(s):  
Huan Li ◽  
Stacy Patterson ◽  
Yuhao Yi ◽  
Zhongzhi Zhang

1990 ◽  
Vol 107 (3) ◽  
pp. 461-473 ◽  
Author(s):  
Reinhard Diestel

Let G be an infinite connected graph. A ray (from ν) in G is a 1-way infinite path in G (with initial vertex ν). An infinite connected subgraph of a ray R ⊂ G is called a tail of R. If X ⊂ G is finite, the infinite component of R\X will be called the tail of R in G\X.


2009 ◽  
Author(s):  
Krishnendu Basuli ◽  
Samar Sen Sarma ◽  
Saptarshi Naskar

2015 ◽  
Vol 22 (04) ◽  
pp. 707-710 ◽  
Author(s):  
Imran Anwar ◽  
Zahid Raza ◽  
Agha Kashif

In this paper, we introduce the concept of the spanning simplicial complex Δs(G) associated to a simple finite connected graph G. We characterize all spanning trees of the uni-cyclic graph Un,m. In particular, we give a formula for computing the Hilbert series and h-vector of the Stanley-Reisner ring k[Δs(Un,m)]. Finally, we prove that the spanning simplicial complex Δs(Un,m) is shifted and hence is shellable.


1954 ◽  
Vol 6 ◽  
pp. 80-91 ◽  
Author(s):  
W. T. Tutte

SummaryTwo polynomials θ(G, n) and ϕ(G, n) connected with the colourings of a graph G or of associated maps are discussed. A result believed to be new is proved for the lesser-known polynomial ϕ(G, n). Attention is called to some unsolved problems concerning ϕ(G, n) which are natural generalizations of the Four Colour Problem from planar graphs to general graphs. A polynomial χ(G, x, y) in two variables x and y, which can be regarded as generalizing both θ(G, n) and ϕ(G, n) is studied. For a connected graph χ(G, x, y) is defined in terms of the “spanning” trees of G (which include every vertex) and in terms of a fixed enumeration of the edges.


2013 ◽  
Vol 68 (8-9) ◽  
pp. 531-538 ◽  
Author(s):  
Kinkar C. Das

Let G be a connected graph of order n with Laplacian eigenvalues μ1 ≥ μ2 ≥ ... ≥ μn-1 > mn = 0. The Kirchhoff index of G is defined as [xxx] In this paper. we give lower and upper bounds on Kf of graphs in terms on n, number of edges, maximum degree, and number of spanning trees. Moreover, we present lower and upper bounds on the Nordhaus-Gaddum-type result for the Kirchhoff index.


2012 ◽  
Vol 263-266 ◽  
pp. 3301-3305
Author(s):  
Bao Lei Cheng ◽  
Jian Xi Fan ◽  
Ji Wen Yang ◽  
Yan Wang ◽  
Shu Kui Zhang

There is a well-known conjecture on independent spanning trees (ISTs) on graphs: For any n-connected graph G with n≥1, there are n ISTs rooted at an arbitrary node on G. It still remains open for n≥5. We propose an integrated algorithm to construct n ISTs rooted at any node similar to 0 or 10n-1 on n-dimensional HCH cube for n≥1 and give the simulations of ISTs on several special BC networks, such as HCH cubes, crossed cubes, Möbius cubes, twisted cubes, etc.


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