Results 31 to 40 of about 91 (80)
Contraharmonic Index: Extremal Results for Unicyclic Graphs and Bounds for General Graphs
Journal of Mathematics, Volume 2026, Issue 1, 2026.Let G be a graph with edge set E(G). The degree of a vertex w in G is denoted by dw. The contraharmonic index of G is defined as CHG=∑uv∈EGdu+dv−1du2+dv2. In this paper, we investigate several properties of the contraharmonic index, including extremal results for unicyclic graphs of a given order, as well as bounds and the effects of an edge removal in
Abdulaziz Mutlaq Alotaibi +2 more
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Degree‐Based Topological Indices of the Jacobson Graph of Zm×Zn×Zr
Journal of Mathematics, Volume 2026, Issue 1, 2026.Let R be a commutative ring with unity. The Jacobson graph IR of R is an undirected simple graph whose vertex set is R\J(R), where J(R) is a Jacobson ideal of R, and for any distinct vertices x, y ∈ R\J(R) are adjacent if and only if 1 − xy is not a unit of R.
Ndago F. Omondi +2 more
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On the Clean Graph of Commutative Artinian Rings
International Journal of Mathematics and Mathematical Sciences, Volume 2025, Issue 1, 2025.For a commutative Artinian ring R with unity, the clean graph Cl(R) is a graph with vertices in the form of an ordered pair (e, u), where e is an idempotent and u is a unit of ring R, respectively. Two distinct vertices (e, u) and (f, v) are adjacent in Cl(R) if and only if ef = fe = 0 or uv = vu = 1.
R. Singh +3 more
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On General Sum‐Connectivity Index and Number of Segments of Fixed‐Order Chemical Trees
Journal of Mathematics, Volume 2025, Issue 1, 2025.Nowadays, one of the most active areas in mathematical chemistry is the study of the mathematical characteristics associated with molecular descriptors. The primary objective of the current study is to find the largest value of χα of graphs in the class of all fixed‐order chemical trees with a particular number of segments for α > 1, where χα is the ...
Muzamil Hanif +5 more
wiley +1 more source
Journal of Mathematics, Volume 2025, Issue 1, 2025.The multiplicative sum Zagreb index of a graph G is defined as the product of the sum of the degrees of adjacent vertices of G. A molecular tree is an acyclic connected graph with maximum degree at most 4. A vertex in a molecular tree with degree 3 or 4 is referred to as a branching vertex. In this paper, we consider the class of all molecular trees of
Sadia Noureen +6 more
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A Constructive Extension of the Characterization on Potentially Ks,t-Bigraphic Pairs
Discussiones Mathematicae Graph Theory, 2017 Let Ks,t be the complete bipartite graph with partite sets of size s and t. Let L1 = ([a1, b1], . . . , [am, bm]) and L2 = ([c1, d1], . . . , [cn, dn]) be two sequences of intervals consisting of nonnegative integers with a1 ≥ a2 ≥ . . . ≥ am and c1 ≥ c2
Guo Ji-Yun, Yin Jian-Hua
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Discussiones Mathematicae Graph Theory, 2018 A digraph is called irregular if its distinct vertices have distinct degree pairs. An irregular digraph is called minimal (maximal) if the removal of any arc (addition of any new arc) results in a non-irregular digraph. It is easily seen that the minimum
Górska Joanna +4 more
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The Bipartite-Splittance of a Bipartite Graph
Discussiones Mathematicae Graph Theory, 2019 A bipartite-split graph is a bipartite graph whose vertex set can be partitioned into a complete bipartite set and an independent set. The bipartite- splittance of an arbitrary bipartite graph is the minimum number of edges to be added or removed in ...
Yin Jian-Hua, Guan Jing-Xin
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Irreversible 2-conversion set in graphs of bounded degree [PDF]
Discrete Mathematics & Theoretical Computer Science, 2017 An irreversible $k$-threshold process (also a $k$-neighbor bootstrap percolation) is a dynamic process on a graph where vertices change color from white to black if they have at least $k$ black neighbors. An irreversible $k$-conversion set of a graph $G$
Jan Kynčl +2 more
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New Formulae for the Decycling Number of Graphs
Discussiones Mathematicae Graph Theory, 2019 A set S of vertices of a graph G is called a decycling set if G−S is acyclic. The minimum order of a decycling set is called the decycling number of G, and denoted by ∇(G). Our results include: (a) For any graph G,, where T is taken over all the spanning
Yang Chao, Ren Han
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