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相关论文: Extremal Bounds on the Sigma and Albertson Indices…

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This study explores the irregularity properties of trees with prescribed degree sequences by analyzing two prominent topological indices: the Albertson index and the sigma index. With a particular emphasis on caterpillar trees -frequently…

组合数学 · 数学 2025-12-16 Jasem Hamoud , Alexey Belov Yakovlevich , Muaadh Almahalebi , Duaa Abdullah

In this paper, we presents novel and sharp bounds on the Albertson index of trees, revealing deep connections between degree sequences and graph irregularity where the Albertson index of Caterpillar tree satisfy \[…

综合数学 · 数学 2025-12-16 Jasem Hamoud , Duaa Abdullah

In this paper, the study of extreme value bounds for topological indices is crucial for understanding their influence on trees and bipartite graphs. For integers $\alpha, p$ satisfying $1 \leq p \leq \alpha \leq \Delta - 3$, the minimum…

组合数学 · 数学 2025-12-16 Jasem Hamoud , Duaa Abdullah

In this paper, we have studied bounds based on topological indicators, from which we selected Albertson index $\mathrm{irr}$ and the Sigma index $\sigma$. The Sigma index was defined through the following relationship: \[…

组合数学 · 数学 2025-06-16 Jasem Hamoud , Alexei Belov-Kanel , Duaa Abdullah

In this paper, degree-based topological indices play a key role in the structural analysis of graphs in this paper and have significant uses in chemical graph theory. We investigate the connections between three such tree indices: the…

组合数学 · 数学 2026-03-10 Duaa Abdullah , Jasem Hamoud

In this paper, we provide the irregularity properties of trees with strong support vertex by analyzing two prominent topological indices: the Albertson index and the Sigma index. We further establish extremal bounds for both indices across…

组合数学 · 数学 2025-05-13 Jasem Hamoud , Duaa Abdullah

In this paper, we presented a study of topological indices on trees, where we show a relationship with irregularity of Albertson index and minimum, maximum degrees $\delta,\Delta$ of graph $G$, where contribute vital roles in determining…

组合数学 · 数学 2025-11-26 Jasem Hamoud , Artem Kornosov

In this paper, we establishe the extremal bounds of the topological indices -- Sigma index -- focusing on analyzing the sharp upper bounds and the lower bounds of the Sigma index, which is known $\sigma(G)=\sum_{uv\in…

组合数学 · 数学 2026-03-31 Jasem Hamoud , Duaa Abdullah

In this paper, topological indices play a significant role in the analysis of caterpillar trees, especially due to their applications in chemical graph theory. We presented a study on topological indices related to the Sigma index, which we…

组合数学 · 数学 2025-12-16 Jasem Hamoud , Duaa Abdullah

The $\sigma$-irregularity index of a graph is defined as the sum of squared degree differences over all edges and provides a sensitive measure of structural heterogeneity. In this paper, we study the problem of maximizing $\sigma(T)$ among…

组合数学 · 数学 2026-02-17 Milan Bašić

In this paper, we refer to a asymptotic degree sequence as $\mathscr{D}=(d_1,d_2,\dots,d_n)$. The examination of topological indices on trees gives us a general overview through bounds to find the maximum and minimum bounds which reflect…

组合数学 · 数学 2025-12-16 Jasem Hamoud , Duaa Abdullah

In this paper, we investigate The relationship between the Albertson index and the first Zagreb index for trees. For a tree $T=(V,E)$ with $n=|V|$ vertices and $m=|E|$ edges, we provide several bounds and exact formulas for these two…

组合数学 · 数学 2025-06-03 Jasem Hamoud , Alexei Belov-Kanel , Duaa Abdullah

In this paper, we investigate the structures of an extremal tree which has the minimal number of subtrees in the set of all trees with the given degree sequence of a tree. In particular, the extremal trees must be caterpillar and but in…

组合数学 · 数学 2012-09-04 Xiu-Mei Zhang , Xiao-Dong Zhang

We obtain sharp lower and upper bounds for the number of maximal (under inclusion) independent sets in trees with fixed number of vertices and diameter. All extremal trees are described up to isomorphism.

组合数学 · 数学 2008-12-31 Alexander Dainiak

The sigma-irregularity index $\sigma(G) = \sum_{uv \in E(G)} (d_G(u) - d_G(v))^2$ measures the total degree imbalance along the edges of a graph. We study extremal problems for $\sigma(T)$ within the class of trees of fixed order $n$ and…

组合数学 · 数学 2026-02-03 Milan Bašić

When considering the number of subtrees of trees, the extremal structures which maximize this number among binary trees and trees with a given maximum degree lead to some interesting facts that correlate to other graphical indices in…

组合数学 · 数学 2012-10-11 Xiu-Mei Zhang , Xiao-Dong Zhang , Daniel Gray , Hua Wang

We estimate the maximum ratio between the $\sigma_t$- and $\sigma$-irregularity for graphs and trees of order $n$, which are respectively bounded by $\Theta(n^{5/2})$ and $n-2$. This answers a question and a conjecture by Filipovski et al.…

组合数学 · 数学 2026-04-29 Stijn Cambie , Jionghua Chang

This paper investigates topological indices for the greedy tree $\mathcal{T}_\mathscr{D}$ associated with a graphic degree sequence $\mathscr{D} = (d_1 \geqslant d_2 \geqslant \dots \geqslant d_n)$ of a tree. A fundamental challenge in the…

综合数学 · 数学 2026-02-05 Jasem Hamoud , Duaa Abdullah

In this paper, the investigates Adriatic indices, specifically the sum lordeg index where it defined as $SL(G) = \sum_{u \in V(G)} \deg_G(u) \sqrt{\ln \deg_G(u)}$ and the variable sum exdeg index $SEI_a(G)$ for $a>0$, $a\neq 1$. We present…

组合数学 · 数学 2025-08-07 Jasem Hamoud , Duaa Abdullah

This paper surveys some recent results and progress on the extremal prob- lems in a given set consisting of all simple connected graphs with the same graphic degree sequence. In particular, we study and characterize the extremal graphs…

组合数学 · 数学 2015-10-08 Xiao-Dong Zhang
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