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The F-index of a graph is defined as the sum of cubes of the vertex degrees of the graph which was introduced in 1972, in the same paper where the first and second Zagreb indices were introduced. In this paper we study the F-index of four…

Discrete Mathematics · Computer Science 2016-11-23 Nilanjan De

Given an edge labeling $f$ of a graph $G$, a vertex $v$ is called an $AR$-vertex, if $v$ has distinct edge weight sums for each distinct subset of edges incident on $v$. An injective edge labeling $f$ of a graph $G$ is called an…

Combinatorics · Mathematics 2025-02-27 Arun J Manattu , Aparna Lakshmanan S

A set-indexer of a graph $G$ is an injective set-valued function $f:V(G) \rightarrow2^{X}$ such that the function $f^{\oplus}:E(G)\rightarrow2^{X}-\{\emptyset\}$ defined by $f^{\oplus}(uv) = f(u){\oplus} f(v)$ for every $uv{\in} E(G)$ is…

Combinatorics · Mathematics 2014-03-25 N. K. Sudev , K. A. Germina

A graph is called integral if all its eigenvalues are integers. A Cayley graph is called normal if its connection set is a union of conjugacy classes. We show that a non-empty integral normal Cayley graph for a group of odd order has an odd…

Combinatorics · Mathematics 2023-12-21 Arnbjörg Soffía Árnadóttir , Chris Godsil

In the present paper, we introduce the concept of universal graph series. We then present four invariants of graphs and discuss some of their properties. In particular, one of these invariants is a generalization of the chromatic symmetric…

Combinatorics · Mathematics 2025-01-22 Tsuyoshi Miezaki , Akihiro Munemasa , Yusaku Nishimura , Tadashi Sakuma , Shuhei Tsujie

Graphs constructed to translate some graph problem into another graph problem are usually called auxiliary graphs. Specifically total graphs of simple graphs are used to translate the total colouring problem of the original graph into a…

General Mathematics · Mathematics 2016-02-16 Ravi Goyal , Mahipal Jadeja , Rahul Muthu

An eigenvalue of a graph $G$ is called a main eigenvalue if it has an eigenvector the sum of whose entries is not equal to zero. It is well known that a graph $G$ has exactly two main eigenvalues if and only if there exists a unique pair of…

Combinatorics · Mathematics 2016-09-20 Lin Chen , Qiongxiang Huang

An integer additive set-indexer is defined as an injective function $f:V(G)\rightarrow 2^{\mathbb{N}_0}$ such that the induced function $g_f:E(G) \rightarrow 2^{\mathbb{N}_0}$ defined by $g_f (uv) = f(u)+ f(v)$ is also injective. An integer…

Combinatorics · Mathematics 2014-06-10 N K Sudev , K A Germina

Let $\Gamma=(V,E)$ be a graph. If all the eigenvalues of the adjacency matrix of the graph $\Gamma$ are integers, then we say that $\Gamma$ is an integral graph. A graph $\Gamma$ is determined by its spectrum if every graph cospectral to it…

Combinatorics · Mathematics 2021-01-22 Jia-Bao Liu , S. Morteza Mirafzal , Ali Zafari

Let $R$ be a finite product of integral domains and $D$ be a union of prime ideals (it is possible that $R$ is just an integral domain). Let $n \geq 1$ be a positive integer. This paper introduces the $n$-total graph of a $(R, D)$. The…

Commutative Algebra · Mathematics 2026-01-19 Myriam AbiHabib , Ayman Badawi

Let $\N$ denote the set of all non-negative integers and $\cP(\N)$ be its power set. An integer additive set-labeling (IASL) of a graph $G$ is an injective set-valued function $f:V(G)\to \cP(\N)-\{\emptyset\}$ such that the induced function…

General Mathematics · Mathematics 2015-11-04 N. K. Sudev , K. A. Germina

A mapping $l : E(G) \rightarrow A$, where $A$ is an abelian group which written additively, is called a labeling of the graph $G$. For every positive integer $h \geqslant 2$, a graph $G$ is said to be zero-sum $h$-magic if there is an edge…

Combinatorics · Mathematics 2020-10-13 Haobai Wang

Suppose the vertices of a graph $G$ were labeled arbitrarily by positive integers, and let $Sum(v)$ denote the sum of labels over all neighbors of vertex $v$. A labeling is lucky if the function $Sum$ is a proper coloring of $G$, that is,…

Combinatorics · Mathematics 2010-10-26 Arash Ahadi , Ali Dehghan , Esmael Mollaahmadi

In this paper, we introduce the concept of $k$-integral graphs. A graph $\Gamma$ is called $k$-integral if the extension degree of the splitting field of the characteristic polynomial of $\Gamma$ over rational field $\mathbb Q$ is equal to…

Combinatorics · Mathematics 2025-08-06 Alireza Abdollahi , Majid Arezoomand , Tao Feng , Shixin Wang

A graph $G$ is asymmetric if its automorphism group of vertices is trivial. Asymmetric graphs were introduced by Erd\H{o}s and R\'{e}nyi in 1963 where they measured the degree of asymmetry of an asymmetric graph. They proved that any…

Combinatorics · Mathematics 2020-07-23 Alejandra Brewer , Adam Gregory , Quindel Jones , Darren A. Narayan

The F-index of a graph $G$ is the sum of the cubes of the degrees of the vertices of $G$. In this paper, explicit expressions for the F-index of different transformation graphs of type ${{G}^{xyz}}$ with $x, y, z\in \{-, + \}$ are obtained.…

Discrete Mathematics · Computer Science 2016-06-21 Nilanjan De

A graph $G$ is called well-covered if all maximal independent sets of vertices have the same cardinality. A well-covered graph $G$ is called uniformly well-covered if there is a partition of the set of vertices of $G$ such that each maximal…

Combinatorics · Mathematics 2013-04-12 Rashid Zaare-Nahandi

Let R be a commutative ring and M be an R-module. We define the large sum graph, denoted by \acute{G}(M), as a graph with the vertex set of non-large submodules of M and two distinct vertices are adjacent if and only if N + K is a non-large…

Commutative Algebra · Mathematics 2019-07-22 H. Ansari-Toroghy , F. Mahboobi-Abkenar

The subspace sum graph $\mathcal{G}(\mathbb{V})$ on a finite dimensional vector space $\mathbb{V}$ was introduced by Das [Subspace Sum Graph of a Vector Space, arXiv:1702.08245], recently. The vertex set of $\mathcal{G}(\mathbb{V})$…

Combinatorics · Mathematics 2017-04-13 Fenglei Tian , Dein Wong

If all the eigenvalues of the Hermitian-adjacency matrix of a mixed graph are integers, then the mixed graph is called \emph{H-integral}. If all the eigenvalues of the (0,1)-adjacency matrix of a mixed graph are \emph{Gaussian integers},…

Combinatorics · Mathematics 2023-02-17 Monu Kadyan , Bikash Bhattacharjya