Abstract

A connected graph in which no edge lies on more than one cycle is called a cactus graph (also known as Husimi tree). A bond incident degree (BID) index of a graph G is defined as ∑ u v ∈ E G f d G u , d G v , where d G w denotes the degree of a vertex w of G , E G is the edge set of G , and f is a real-valued symmetric function. This study involves extremal results of cactus graphs concerning the following type of the BID indices: I f i G = ∑ u v ∈ E G f i d G u / d G u + f i d G v / d G v , where i ∈ 1,2 , f 1 is a strictly convex function, and f 2 is a strictly concave function. More precisely, graphs attaining the minimum and maximum I f i values are studied in the class of all cactus graphs with a given number of vertices and cycles. The obtained results cover several well-known indices including the general zeroth-order Randić index, multiplicative first and second Zagreb indices, and variable sum exdeg index.

Highlights

  • All the graphs considered in this study are connected. e notation and terminology that are used in this study but not defined here can be found in some standard graph-theoretical books [6, 7].Graph invariants of the following form are known as the bond incident degree (BID) indices [5]: BID(G) 􏽘 f dG(u), dG(v)􏼁, (1) uv∈E(G)where dG(w) denotes the degree of a vertex w ∈ V(G) of the graph G, E(G) is the edge set of G, and f is a real-valued symmetric function

  • We are concerned with the following type [2] of the BID indices: Ifi(G)

  • We study the graphs attaining the minimum and maximum Ifi values from the class of all cactus graphs with a given number of vertices and cycles

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Summary

Research Article Some Bond Incident Degree Indices of Cactus Graphs

Akbar Ali ,1 Akhlaq Ahmad Bhatti, Naveed Iqbal ,1 Tariq Alraqad ,1 Jaya Percival Mazorodze ,3 Hicham Saber, and Abdulaziz M. A connected graph in which no edge lies on more than one cycle is called a cactus graph ( known as Husimi tree). A bond incident degree (BID) index of a graph G is defined as 􏽐uv∈E(G)f(dG(u), dG(v)), where dG(w) denotes the degree of a vertex w of G, E(G) is the edge set of G, and f is a real-valued symmetric function. Is study involves extremal results of cactus graphs concerning the following type of the BID indices: Ifi(G) 􏽐uv∈E(G)[fi(dG(u))/dG(u) + fi(dG(v))/dG(v)], where i ∈ {1, 2}, f1 is a strictly convex function, and f2 is a strictly concave function. Graphs attaining the minimum and maximum Ifi values are studied in the class of all cactus graphs with a given number of vertices and cycles. Graphs attaining the minimum and maximum Ifi values are studied in the class of all cactus graphs with a given number of vertices and cycles. e obtained results cover several well-known indices including the general zeroth-order Randicindex, multiplicative first and second Zagreb indices, and variable sum exdeg index

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