Open Journal of Discrete Applied Mathematics (ODAM)

Classical graph theory represents pairwise relationships using vertices and edges, while hypergraphs extend this model by allowing hyperedges to join any number of vertices, enabling complex multi‐way connections. SuperHyperGraphs further generalize hypergraphs through iterated powerset constructions, capturing hierarchical relationships at multiple layers. Weighted and signed graph models assign numerical weights or positive/negative signs to edges, respectively, and these concepts have been lifted to hypergraphs and, more recently, to SuperHyperGraphs. In this paper, we systematically develop the definitions and core properties of weighted SuperHyperGraphs and signed SuperHyperGraphs. We provide detailed examples to illustrate their structure and discuss potential applications in modeling layered networks with quantitative and polarity annotations. Our results lay a foundation for future theoretical and algorithmic advances in this emerging area.

World Bank macrodata for every country on our planet indicate that national incomes per capita account for a significant portion of population disparity, and these incomes follow well-known distributions documented in the literature across almost all continents. Measuring and comparing disparity is a substantial task that requires assembling the relative nature of both small and large national incomes without distinctions. This is the primary reason we consider the Atkinson inequality index (in the continuous case) in this paper, which was developed towards the end of the 20th century to measure this disparity. Since then, a nonparametric estimator for the Atkinson index has not been developed; instead, a well-known classical discrete form has been utilized. This reliance on the classical form makes the estimation or measurement of economic inequalities relatively straightforward. In this paper, we construct a kernel estimator of the Atkinson inequality index and, by extension, that of its associated welfare function. We then establish their almost sure asymptotic convergence. Finally, we explore the performance of our estimators through a simulation study and draw conclusions about national incomes per capita on each continent, as well as globally, by making comparisons with the classical form based on World Bank staff estimates derived from sources and methods outlined in “The Changing Wealth of Nations”. The results obtained highlight the advantages of kernel-based measures and the sensitivity of the index concerning the aversion parameter.

Let \(E(G)\) and \(d_x\) denote the edge set and degree of a vertex \(x\) in \(G\), respectively. Recently, the elliptic Sombor index has been defined as \[ESO(G) = \sum_{xy \in E(G)} (d_x + d_y) \sqrt{d_x^2 + d_y^2}\,.\] A molecular tree is a tree in which the maximum degree does not exceed \(4\). In this paper, we establish sharp upper and lower bounds for the \(ESO\) index in the class of molecular trees with order \(n\) and exactly \(k\) vertices of maximum degree \(\Delta \geq 2\). Moreover, we completely characterize the extremal trees attaining these bounds. Our findings contribute to the structural analysis of molecular trees and further the understanding of the elliptic Sombor index in chemical graph theory.

Zaslavsky (1991) characterized all single-element coextensions of graphic matroids in terms of a graphical structure called a biased graph. In this paper we characterize all orientations of a single-element coextension of a graphic matroid in terms of graphically defined orientations of its associated biased graph.

The exact deg-centric graph of a simple graph \(G\), denoted by \(G_{ed}\), is a graph constructed from \(G\) such that \(V(G_{ed}) = V(G)\) and \(E(G_{ed}) = \{v_iv_j: d_G(v_i,v_j) = deg_G(v_i)\}\). This research note presents the domination numbers of both the Jaco graph \(J_n(x)\) and the exact deg-centric graph of the family of Jaco graphs. The respective complement graphs are also addressed.

The first Zagreb index of a graph is one of the most important topological indices in chemical graph theory. It is also an important invariant of general graphs. The first Zagreb index of a graph is defined as the sum of the squares of the degrees of the vertices in the graph. The research on the Hamiltonian properties of a graph is an important topic in graph theory. Use the Diaz-Metcalf inequality, we in this paper present new sufficient conditions based on the first Zagreb index for the Hamiltonian and traceable graphs. In addition, using the ideas of obtaining the sufficient conditions, we also present an upper bound for the first Zagreb index of a graph. The graphs achieving the upper bound are also characterized.

This paper introduces the concept of the extended \(H\)-cover of a graph \(G\), denoted as \(G^*_H\) , as a generalization inspired by the extended double cover graphs discussed in Chen [1]. We explore the spectral properties and energy characteristics of \(G^*_H\), deriving formulae for the number of spanning trees in cases where both \(G\) and \(H\) are regular. Our investigation identifies several infinite families of equienergetic graphs and highlights instances of cospectral graphs within \(G^*_H\) . Additionally, we analyze various graph parameters related to the Indu-Bala product of graphs and the partial complement of the subdivision graph (PCSD) of \(G\).

A dominator coloring of a graph \(\mathscr{G}\) is a proper coloring where each vertex of \(\mathscr{G}\) is within the closed neighborhood of at least one vertex from each color class. The minimum number of color classes required for a dominator coloring of \(\mathscr{G}\) is termed the dominator chromatic number. Additionally, a total dominator coloring of a graph \(\mathscr{G}\) is a proper coloring in which every vertex dominates at least one color class other than its own. The minimum number of color classes needed for a total dominator coloring of \(\mathscr{G}\) is known as the total dominator chromatic number. In this paper, our objective is to derive findings concerning dominator and total dominator coloring of the duplication corresponding corona of specific graphs.

The topological index is a molecular property that is determined from a chemical compound’s molecular graph. Topological indices are numerical graph parameters that inform us about the topology of the graph and are generally graph invariants. In this paper, we consider some topological indices based on the second distance of each vertex of the graph \(\alpha\) and the number of unordered pairs of vertices \(\{s,q\} \subseteq V(\alpha)\) which are at distance \(3\) in \(\alpha\). These indices are called the leap Zagreb index and the Wiener polarity index, respectively. we compute these indices of \(R\)-vertex join and \(R\)-edge join of graphs.

A novel topological index, the Sombor index, has been proposed by Ivan Gutman in a recent paper [1]. Motivated by this novel index, we study the new variants of Sombor index and to examine the correlation of newly introduced topological indices we have computed the values of these indices by taking all possible trees on 10 vertices. Here in this paper, we derive explicit formulae for the Sombor index of various nanostructures. These include hexagonal parallelogram \( P(\alpha, \beta) \)-nanotubes, triangular benzenoid \( G_{\alpha} \), and zigzag-edge coronoid fused with starphene nanotubes \( ZCS(k,\alpha,\beta) \), where \( k, \alpha, \beta \) are natural numbers. We also compute the Sombor index for dominating derived networks \( D_{1}, D_{2}, D_{3} \), as well as for various dendrimers such as Porphyrin Dendrimer, Ninc-Porphyrin Dendrimer, Propyl Ether Imine Dendrimers, and Polyamidoamin (PAMAM) Dendrimer. Additionally, we examine Polyamidoamin dendrimers (\( PD_{1}, PD_{2}, DS_{1} \)) and linear polyomino chains like \( L_{\alpha} \), \( Z_{\alpha} \), \( B^{1}_{\alpha}(\alpha \geq 3) \), \( B^{2}_{\alpha}(\alpha \geq 4) \). Finally, we consider benzenoid systems with different shapes, including triangular, hourglass, and jagged-rectangle configurations. By computing the Sombor index for these nanostructures, we provide a comprehensive analysis of their topological properties.