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DM
2002
86views more  DM 2002»
14 years 7 days ago
A chip-firing game and Dirichlet eigenvalues
We consider a variation of the chip-firing game in a induced subgraph S of a graph G. Starting from a given chip configuration, if a vertex v has at least as many chips as its deg...
Fan R. K. Chung, Robert B. Ellis
JGT
2007
130views more  JGT 2007»
14 years 10 days ago
Vertex partitions and maximum degenerate subgraphs
: Let G be a graph with maximum degree d ≥ 3 and ω(G) ≤ d, where ω(G) is the clique number of the graph G. Let p1 and p2 be two positive integers such that d = p1 + p2. In th...
Martín Matamala
JCT
2007
96views more  JCT 2007»
14 years 10 days ago
Induced subgraphs of Ramsey graphs with many distinct degrees
An induced subgraph is called homogeneous if it is either a clique or an independent set. Let hom(G) denote the size of the largest homogeneous subgraph of a graph G. In this shor...
Boris Bukh, Benny Sudakov
JCT
2007
94views more  JCT 2007»
14 years 10 days ago
A zero-free interval for flow polynomials of cubic graphs
Let P(G,t) and F(G,t) denote the chromatic and flow polynomials of a graph G. D.R. Woodall has shown that, if G is a plane triangulation, then the only zeros of P(G,t) in (−∞...
Bill Jackson
CPC
2007
88views more  CPC 2007»
14 years 12 days ago
Zero-Free Intervals for Flow Polynomials of Near-Cubic Graphs
Let P(G,t) and F(G,t) denote the chromatic and flow polynomials of a graph G. G.D. Birkhoff and D.C. Lewis showed that, if G is a plane near triangulation, then the only zeros of...
Bill Jackson
JCT
2008
85views more  JCT 2008»
14 years 12 days ago
Smith normal form and Laplacians
Let M denote the Laplacian matrix of a graph G. Associated with G is a finite group (G), obtained from the Smith normal form of M, and whose order is the number of spanning trees o...
Dino J. Lorenzini
COMBINATORICS
2007
100views more  COMBINATORICS 2007»
14 years 13 days ago
Revisiting Two Classical Results on Graph Spectra
Let µ (G) and µmin (G) be the largest and smallest eigenvalues of the adjacency matrix of a graph G. Our main results are: (i) If H is a proper subgraph of a connected graph G o...
Vladimir Nikiforov
COMBINATORICS
2007
99views more  COMBINATORICS 2007»
14 years 13 days ago
The Spectral Radius of Subgraphs of Regular Graphs
Let µ (G) and µmin (G) be the largest and smallest eigenvalues of the adjacency matrix of a graph G. Our main results are: (i) Let G be a regular graph of order n and finite di...
Vladimir Nikiforov
ENDM
2006
127views more  ENDM 2006»
14 years 13 days ago
Greedy defining sets in graphs and Latin squares
Greedy algorithm sometimes uses more than (G) colors while coloring a graph G. A greedy defining set is an object to eliminate these extra colors so that the greedy coloring resul...
Manouchehr Zaker
DCG
2010
80views more  DCG 2010»
14 years 16 days ago
Geometry of Configuration Spaces of Tensegrities
Consider a graph G with n vertices. In this paper we study geometric conditions for an n-tuple of points in Rd to admit a non-zero self stress with underlying graph G. We introduce...
Franck Doray, Oleg Karpenkov, Jan Schepers