scholarly journals Stability number and chromatic number of tolerance graphs

1992 ◽  
Vol 36 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Giri Narasimhan ◽  
Rachel Manber
Keyword(s):  
Chromatic Number ◽  
Stability Number ◽  
Tolerance Graphs

The Strong Perfect Graph Conjecture for Planar Graphs

1973 ◽  
Vol 25 (1) ◽  
pp. 103-114 ◽  
Author(s):  
Alan Tucker
Keyword(s):  
Chromatic Number ◽  
Planar Graphs ◽  
Independent Set ◽  
Independent Sets ◽  
Clique Number ◽  
Perfect Graph ◽  
Stability Number ◽  
Partition Number ◽  
Minimum Number ◽  
The Stability

A graph G is called γ-perfect if ƛ (H) = γ(H) for every vertex-generated subgraph H of G. Here, ƛ(H) is the clique number of H (the size of the largest clique of H) and γ(H) is the chromatic number of H (the minimum number of independent sets of vertices that cover all vertices of H). A graph G is called α-perfect if α(H) = θ(H) for every vertex-generated subgraph H of G, where α (H) is the stability number of H (the size of the largest independent set of H) and θ(H) is the partition number of H (the minimum number of cliques that cover all vertices of H).

scholarly journals A Superlocal Version of Reed's Conjecture

10.37236/2666 ◽  
2014 ◽  
Vol 21 (4) ◽  
Author(s):  
Katherine Edwards ◽  
Andrew D. King
Keyword(s):  
Chromatic Number ◽  
Stable Set ◽  
Line Graphs ◽  
Stability Number ◽  
Single Vertex ◽  
Fractional Relaxation

Reed's well-known $\omega$, $\Delta$, $\chi$ conjecture proposes that every graph satisfies $\chi \leq \lceil \frac 12(\Delta+1+\omega)\rceil$. The second author formulated a local strengthening of this conjecture that considers a bound supplied by the neighbourhood of a single vertex. Following the idea that the chromatic number cannot be greatly affected by any particular stable set of vertices, we propose a further strengthening that considers a bound supplied by the neighbourhoods of two adjacent vertices. We provide some fundamental evidence in support, namely that the stronger bound holds in the fractional relaxation and holds for both quasi-line graphs and graphs with stability number two. We also conjecture that in the fractional version, we can push the locality even further.

scholarly journals Blockers for the Stability Number and the Chromatic Number

2013 ◽  
Vol 31 (1) ◽  
pp. 73-90 ◽  
Author(s):  
C. Bazgan ◽  
C. Bentz ◽  
C. Picouleau ◽  
B. Ries
Keyword(s):  
Chromatic Number ◽  
Stability Number ◽  
The Stability

scholarly journals Getting new algorithmic results by extending distance-hereditary graphs via split composition

2021 ◽  
Vol 7 ◽  
pp. e627
Author(s):  
Serafino Cicerone ◽  
Gabriele Di Stefano
Keyword(s):  
Chromatic Number ◽  
Domination Number ◽  
Graph Isomorphism ◽  
Clique Number ◽  
Efficient Algorithms ◽  
Combinatorial Problems ◽  
Stability Number ◽  
New Class ◽  
Graph Classes ◽  
Graph Class

In this paper, we consider the graph class denoted as Gen(∗;P3,C3,C5). It contains all graphs that can be generated by the split composition operation using path P3, cycle C3, and any cycle C5 as components. This graph class extends the well-known class of distance-hereditary graphs, which corresponds, according to the adopted generative notation, to Gen(∗;P3,C3). We also use the concept of stretch number for providing a relationship between Gen(∗;P3,C3) and the hierarchy formed by the graph classes DH(k), with k ≥1, where DH(1) also coincides with the class of distance-hereditary graphs. For the addressed graph class, we prove there exist efficient algorithms for several basic combinatorial problems, like recognition, stretch number, stability number, clique number, domination number, chromatic number, and graph isomorphism. We also prove that graphs in the new class have bounded clique-width.

ON GRAPHS WITH LIMITED NUMBER OF P4-PARTNERS

1999 ◽  
Vol 10 (01) ◽  
pp. 103-121 ◽  
Author(s):  
FLORIAN ROUSSEL ◽  
IRENA RUSU ◽  
HENRI THUILLIER
Keyword(s):  
Chromatic Number ◽  
Optimization Problems ◽  
Linear Time ◽  
Clique Number ◽  
Recognition Algorithm ◽  
Stability Number

The study of graphs containing few P4's generated an important number of results related to perfection, recognition, optimization problems (see [12], [15], [8]). We define here a new, larger class of graphs and show that the indicated problems may be efficiently solved on this class too (thus generalizing some of the previous results). Namely, we give a linear time recognition algorithm for this class and we note that the optimization problems concerning the clique number, stability number, chromatic number and clique cover number are solvable in linear time.

Tolerance Graphs

2004 ◽  
Author(s):  
Martin Charles Golumbic ◽  
Ann N. Trenk
Keyword(s):  
Tolerance Graphs

Packing Chromatic Number of Cycle Related Graphs

2014 ◽  
Vol 4 (1) ◽  
pp. 27
Author(s):  
Albert William ◽  
Roy Santiago ◽  
Indra Rajasingh
Keyword(s):  
Chromatic Number ◽  
Packing Chromatic Number

Packing coloring on subdivision-vertex and subdivision-edge join of cycle Cm with path Pn

2020 ◽  
pp. 627-634
Author(s):  
K. Rajalakshmi ◽  
M. Venkatachalam ◽  
M. Barani ◽  
D. Dafik
Keyword(s):  
Chromatic Number ◽  
Path Graph ◽  
Packing Chromatic Number ◽  
Cycle Graph

The packing chromatic number $\chi_\rho$ of a graph $G$ is the smallest integer $k$ for which there exists a mapping $\pi$ from $V(G)$ to $\{1,2,...,k\}$ such that any two vertices of color $i$ are at distance at least $i+1$. In this paper, the authors find the packing chromatic number of subdivision vertex join of cycle graph with path graph and subdivision edge join of cycle graph with path graph.

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