The objective of this paper is to finds the lower and upper bounds Nordhaus-Gaddum inequalities fuzzy chromatic number for anti-fuzzy graph. This analyzes index complementary anti graphs in some cases. A theorem proved graph be k-critical. Examples are provided derive vertex coloring these graphs.

Let G be a graph with n vertices. We denote the largest signless Laplacian eigenvalue of G by q1(G) and Laplacian eigenvalues of G by μ1(G) > · · · > μn−1(G) > μn(G) = 0. It is a conjecture on Laplacian spread of graphs that μ1(G)−μn−1(G) 6 n − 1 or equivalently μ1(G) + μ1(G) 6 2n − 1. We prove the conjecture for bipartite graphs. Also we show that for any bipartite graph G, μ1(G)μ1(G) 6 n(n − ...

The vertex-degree function index Hf(Γ) is defined as Hf(Γ)=∑v∈V(Γ)f(d(v)) for a f(x) on non-negative real numbers. In this paper, we determine the extremal graphs with maximum (minimum) vertex degree in set of all n-vertex chemical trees, and connected graphs. We also present Nordhaus–Gaddum-type results Hf(Γ)+Hf(Γ¯) Hf(Γ)·Hf(Γ¯).

Topological indices play an important role in Mathematical Chemistry especially in the quantitative structure-property relationship (QSPR) and quantitative structureactivity relationship (QSAR). Recent research indicates that the augmented Zagreb index (AZI) possess the best correlating ability among several topological indices. The main purpose of the current study is to establish some mathema...

Abstract The $\chi $ -stability index $\mathrm {es}_{\chi }(G)$ of a graph G is the minimum number its edges whose removal results in with chromatic smaller than that . We consider three open problems from Akbari et al. [‘Nordhaus–Gaddum and other bounds for edge-stability number’, European J. Combin. 84 (2020), Article no. 103042]. show by examples known characterisation k -regular ( $k\le 5$ ...

Let G be a connected graph with vertex set V.G/. The degree Kirchhoff index of G is defined as S .G/D P fu;vg V.G/ d.u/d.v/R.u;v/, where d.u/ is the degree of vertex u, and R.u;v/ denotes the resistance distance between vertices u and v. In this paper we obtain some upper and lower bounds for the degree Kirchhoff index of graphs. We also obtain some bounds for the Nordhaus-Gaddum-type result fo...

The fractional matching number of a graph G , written as α ′ ( ) is the maximum size . following sharp lower bounds for order n are proved, and all extremal graphs characterized in this paper. (1) + ¯ ≥ 2 (2) If non-empty, then 30 1 (3) have no isolated vertices, 4

the emph{harary index} $h(g)$ of a connected graph $g$ is defined as $h(g)=sum_{u,vin v(g)}frac{1}{d_g(u,v)}$ where $d_g(u,v)$ is the distance between vertices $u$ and $v$ of $g$. the steiner distance in a graph, introduced by chartrand et al. in 1989, is a natural generalization of the concept of classical graph distance. for a connected graph $g$ of order at least $2$ and $ssubseteq v(g)$, th...