scholarly journals Graphs of low chordality

2005 ◽  
Vol Vol. 7 ◽  
Author(s):  
Sunil Chandran ◽  
Vadim V. Lozin ◽  
C.R. Subramanian
Keyword(s):  
Chordal Graphs ◽  
Circle Graphs ◽  
Circular Arc ◽  
International Audience ◽  
Circular Arc Graphs

International audience The chordality of a graph with at least one cycle is the length of the longest induced cycle in it. The odd (even) chordality is defined to be the length of the longest induced odd (even) cycle in it. Chordal graphs have chordality at most 3. We show that co-circular-arc graphs and co-circle graphs have even chordality at most 4. We also identify few other classes of graphs having bounded (by a constant) chordality values.

scholarly journals Structural results on circular-arc graphs and circle graphs: A survey and the main open problems

2014 ◽  
Vol 164 ◽  
pp. 427-443 ◽  
Author(s):  
Guillermo Durán ◽  
Luciano N. Grippo ◽  
Martín D. Safe
Keyword(s):  
Open Problems ◽  
Circle Graphs ◽  
Circular Arc ◽  
Circular Arc Graphs

scholarly journals Isomorphism of graph classes related to the circular-ones property

2013 ◽  
Vol Vol. 15 no. 1 (Discrete Algorithms) ◽  
Author(s):  
Andrew R. Curtis ◽  
Min Chih Lin ◽  
Ross M. Mcconnell ◽  
Yahav Nussbaum ◽  
Francisco Juan Soulignac ◽  
...  
Keyword(s):  
Linear Time ◽  
Time Algorithm ◽  
Linear Time Algorithm ◽  
Circular Arc ◽  
Graph Classes ◽  
Discrete Algorithms ◽  
International Audience ◽  
Related Graph ◽  
Circular Arc Graphs ◽  
Proper Circular Arc Graphs

Discrete Algorithms International audience We give a linear-time algorithm that checks for isomorphism between two 0-1 matrices that obey the circular-ones property. Our algorithm is similar to the isomorphism algorithm for interval graphs of Lueker and Booth, but works on PC trees, which are unrooted and have a cyclic nature, rather than with PQ trees, which are rooted. This algorithm leads to linear-time isomorphism algorithms for related graph classes, including Helly circular-arc graphs, Γ circular-arc graphs, proper circular-arc graphs and convex-round graphs.

scholarly journals Novel Procedures for Graph Edge-colouring

2019 ◽  
Author(s):  
Leandro M. Zatesko ◽  
Renato Carmo ◽  
André L. P. Guedes
Keyword(s):  
Uniform Distribution ◽  
Polynomial Time ◽  
Chordal Graphs ◽  
Circular Arc ◽  
Simple Graphs ◽  
Degree Sum ◽  
Local Degree ◽  
Polynomial Time Algorithms ◽  
Circular Arc Graphs ◽  
Edge Colouring

We present a novel recolouring procedure for graph edge-colouring. We show that all graphs whose vertices have local degree sum not too large can be optimally edge-coloured in polynomial time. We also show that the set ofthe graphs satisfying this condition includes almost every graph (under the uniform distribution). We present further results on edge-colouring join graphs, chordal graphs, circular-arc graphs, and complementary prisms, whose proofs yield polynomial-time algorithms. Our results contribute towards settling the Over- full Conjecture, the main open conjecture on edge-colouring simple graphs. Fi- nally, we also present some results on total colouring.

An Introduction to Intersection Graphs

2020 ◽  
pp. 24-65 ◽  
Author(s):  
Madhumangal Pal
Keyword(s):  
Interval Graphs ◽  
Chordal Graphs ◽  
Intersection Graph ◽  
Important Class ◽  
Intersection Graphs ◽  
Permutation Graphs ◽  
Circular Arc ◽  
String Graphs ◽  
Circular Arc Graphs ◽  
Trapezoid Graphs

In this chapter, a very important class of graphs called intersection graph is introduced. Based on the geometrical representation, many different types of intersection graphs can be defined with interesting properties. Some of them—interval graphs, circular-arc graphs, permutation graphs, trapezoid graphs, chordal graphs, line graphs, disk graphs, string graphs—are presented here. A brief introduction of each of these intersection graphs along with some basic properties and algorithmic status are investigated.

scholarly journals Balancedness of subclasses of circular-arc graphs

2014 ◽  
Vol Vol. 16 no. 3 (Graph Theory) ◽  
Author(s):  
Flavia Bonomo ◽  
Guillermo Duran ◽  
Martın D. Safe ◽  
Annegret K. Wagler
Keyword(s):  
Incidence Matrix ◽  
Perfect Graphs ◽  
Induced Subgraphs ◽  
Circular Arc ◽  
Forbidden Induced Subgraphs ◽  
Odd Order ◽  
International Audience ◽  
Circular Arc Graphs ◽  
Balanced Graphs

Graph Theory International audience A graph is balanced if its clique-vertex incidence matrix contains no square submatrix of odd order with exactly two ones per row and per column. There is a characterization of balanced graphs by forbidden induced subgraphs, but no characterization by mininal forbidden induced subgraphs is known, not even for the case of circular-arc graphs. A circular-arc graph is the intersection graph of a family of arcs on a circle. In this work, we characterize when a given graph G is balanced in terms of minimal forbidden induced subgraphs, by restricting the analysis to the case where G belongs to certain classes of circular-arc graphs, including Helly circular-arc graphs, claw-free circular-arc graphs, and gem-free circular-arc graphs. In the case of gem-free circular-arc graphs, analogous characterizations are derived for two superclasses of balanced graphs: clique-perfect graphs and coordinated graphs.

Surjective L (2, 1)-labeling of cycles and circular-arc graphs

2018 ◽  
Vol 35 (1) ◽  
pp. 739-748 ◽  
Author(s):  
Sk. Amanathulla ◽  
Madhumangal Pal
Keyword(s):  
Circular Arc ◽  
Circular Arc Graphs

An $O(n^2 )$ Algorithm for Coloring Proper Circular Arc Graphs

1981 ◽  
Vol 2 (2) ◽  
pp. 88-93 ◽  
Author(s):  
James B. Orlin ◽  
Maurizio A. Bonuccelli ◽  
Daniel P. Bovet
Keyword(s):  
Circular Arc ◽  
Circular Arc Graphs ◽  
Proper Circular Arc Graphs
Sign in / Sign up

Export Citation Format

Share Document