Mathematical Problems in Engineering

Mathematical Problems in Engineering / 2020 / Article
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Graph-Theoretic Techniques for the Study of Structures or Networks in Engineering

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Research Article | Open Access

Volume 2020 |Article ID 2462530 |

Yun Liu, Aysha Siddiqa, Yu-Ming Chu, Muhammad Azam, Muhammad Asim Raza Basra, Abaid Ur Rehman Virk, "Irregularity Measures for Benzene Ring Embedded in P-Type Surface", Mathematical Problems in Engineering, vol. 2020, Article ID 2462530, 13 pages, 2020.

Irregularity Measures for Benzene Ring Embedded in P-Type Surface

Academic Editor: Jia-Bao Liu
Received22 Jun 2020
Accepted31 Jul 2020
Published26 Aug 2020


A topological index is an important tool in predicting physicochemical properties of a chemical compound. Topological indices help us to assign a single number to a chemical compound. Drugs and other chemical compounds are frequently demonstrated as different polygonal shapes, trees, graphs, etc. In this paper, we will compute irregularity indices for the benzene ring embedded in a P-type surface and the simple bounded dual of the benzene ring embedded in a P-type surface .

1. Introduction

ÓKeeffe et al. [1] have dispersed around a quarter century ago a letter executing two 3D classification of benzene. From which, one is called 6.82P (polybenzene) and has a place with the space gather Im3m, contrast to the P-type surface, and this is due to an insertion of the hexagon fix in the surface of negative ebb and flow P. The P-type surface is facilitated to the Cartesian organizes in the Euclidean space. For further detail about this recurring surface, the author is referred to [2, 3]. This structure needed to be joined as 3D carbon solids; be that as it may, according to our knowledge, no such sequence was assumed before. The goal was to provoke the devotion of scientists to the atomic acknowledgment of such amiable thoughts in carbon nanoscience, as the graphenes took up a moment Nobel prize after C60, and also the immediate union of fullerenes is presently a reality, see for detail [4, 5].

Graph theory provides an interesting appliance in mathematical chemistry where it is used to compute the various kinds of chemical compounds and predict their various properties. One of the most important tools in the chemical graph theory is the topological index, which is useful in predicting the chemical and physical properties of the underlying chemical compound, such as boiling point, strain energy, rigidity, heat of evaporation, and tension [6, 7]. A graph having no loop or multiple edge in known as a simple graph. A molecular graph is a simple graph in which atoms and bounds are represented by vertices and edges, respectively. The degree of the vertex is the number of edges attached with that vertex. These properties of various objects are of primary interest. Winner, in 1947, introduced the concept of the first topological index while finding the boiling point. In 1975, Gutman gave a remarkable identity [8] about Zagreb indices. Hence, these two indices are among the oldest degree-based descriptors, and their properties are extensively investigated. The mathematical formulae of these indices are

A topological index is known as an irregularity index [9] if the value of the topological index of the graph is greater than or equal to zero, and the topological index of the graph is equal to zero if and only if the graph is regular. The irregularity indices are given in Table 1. Most of the irregularity indices are from the family of degree-based topological indices and are used in quantitative structure activity relationship modeling.

Irregularity indexMathematical form


For more about topological indices, one can read [1033].

2. Irregularity Indices for

This section is about irregularity indices of . The molecular graph of is given in Figure 1. We can observe from Figure 1 that there are two types of vertices present in the molecular graph of i.e., 2 and 3. The cardinality of the edge set is .

The edge partition of is given in Table 2.


(2,2)4p + 4q
(3,3)16pq − 6p − 6q

Theorem 1. Let be . The irregularity indices are(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)


3. Irregularity Indices for

Here, we will discuss the irregularity indices for . The molecular graph of is given in Figures 2 and 3. The cardinalities of different types of edges are given in Table 3. The cardinality of the edge set of is (Figure 4).

The edge partition of is given in Table 3.


(2,7)8p + 8q − 24
(4,7)8p + 8q − 24
(4,8)16pq − 24p − 24q + 36
(7,7)4p + 4q − 16
(7,8)4p + 4q − 12
(8,8)24pq − 14p − 14q + 8

Theorem 2. Let be . The irregularity indices are(1)(2)(3)(4)(5)(6)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)