Results 31 to 40 of about 27,017 (285)
About Structure of Graph Obstructions for Klein Surface with 9 Vertices
Кібернетика та комп'ютерні технології, 2020 The structure of the 9 vertex obstructive graphs for the nonorientable surface of the genus 2 is established by the method of (-transformations of the graphs.
V.I. Petrenjuk, D.A. Petrenjuk
doaj +1 more source
Strongly Multiplicative Labeling of Diamond Graph, Generalized Petersen Graph, and Some Other Graphs
Journal of Mathematics, 2022 A finite, simple graph of order k is said to be a strongly multiplicative graph when all vertices of the graph are labeled by positive integers 1,2,3,…,k such that the induced edge labels of the graph, obtained by the product of labels of end vertices of
Sumiya Nasir +5 more
doaj +1 more source
Hosoya Polynomial, Wiener Index, Coloring and Planar of Annihilator Graph of Zn [PDF]
Al-Rafidain Journal of Computer Sciences and Mathematics, 2020 Let R be a commutative ring with identity. We consider ΓB(R) an annihilator graph of the commutative ring R. In this paper, we find Hosoya polynomial, Wiener index, Coloring, and Planar annihilator graph of Zn denote ΓB(Zn) , with n= pm or n=pmq, where p,
Mohammed Ahmed +2 more
doaj +1 more source
Tuza's Conjecture for Threshold Graphs [PDF]
Discrete Mathematics & Theoretical Computer Science, 2022 Tuza famously conjectured in 1981 that in a graph without k+1 edge-disjoint triangles, it suffices to delete at most 2k edges to obtain a triangle-free graph. The conjecture holds for graphs with small treewidth or small maximum average degree, including
Marthe Bonamy +6 more
doaj +1 more source
A Sufficient Condition for Planar Graphs of Maximum Degree 6 to be Totally 7-Colorable
Discrete Dynamics in Nature and Society, 2020 A total k-coloring of a graph is an assignment of k colors to its vertices and edges such that no two adjacent or incident elements receive the same color.
Enqiang Zhu, Yongsheng Rao
doaj +1 more source
The Book Thickness of 1-Planar Graphs is Constant [PDF]
Algorithmica, 2016 In a book embedding, the vertices of a graph are placed on the spine of a book and the edges are assigned to pages, so that edges on the same page do not cross. In this paper, we prove that every $1$-planar graph (that is, a graph that can be drawn on the plane such that no edge is crossed more than once) admits an embedding in a book with constant ...
Bekos, Michael A. +3 more
openaire +3 more sources
1-Planarity of Graphs with a Rotation System
Journal of Graph Algorithms and Applications, 2015 Summary: A graph is 1-planar if it can be drawn in the plane such that each edge is crossed at most once. 1-planarity is known NP-hard, even for graphs of bounded bandwidth, pathwidth, or treewidth, and for near-planar graphs in which an edge is added to a planar graph. On the other hand, there is a linear time 1-planarity testing algorithm for maximal
Auer, Christopher +3 more
openaire +2 more sources
Longer Cycles in Essentially 4-Connected Planar Graphs
Discussiones Mathematicae Graph Theory, 2020 A planar 3-connected graph G is called essentially 4-connected if, for every 3-separator S, at least one of the two components of G − S is an isolated vertex.
Fabrici Igor +3 more
doaj +1 more source
Planar graphs with $\Delta \geq 7$ and no triangle adjacent to a $C_4$ are minimally edge and total choosable [PDF]
Discrete Mathematics & Theoretical Computer Science, 2016 For planar graphs, we consider the problems of list edge coloring and list total coloring. Edge coloring is the problem of coloring the edges while ensuring that two edges that are adjacent receive different colors.
Marthe Bonamy +2 more
doaj +1 more source
On Edge Colorings of 1-Planar Graphs without 5-Cycles with Two Chords
Discussiones Mathematicae Graph Theory, 2019 A graph is 1-planar if it can be drawn on the plane so that each edge is crossed by at most one other edge. In this paper, it is proved that every 1-planar graph with maximum degree ∆ ≥ 8 is edge-colorable with ∆ colors if each of its 5-cycles contains ...
Sun Lin, Wu Jianliang
doaj +1 more source