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Path homology plays a central role in digraph topology and GLMY theory more general. Unfortunately, the computation of the path homology of a digraph $G$ is a two-step process, and until now no complete description of even the underlying…

Algebraic Topology · Mathematics 2024-11-15 Matthew Burfitt , Tyrone Cutler

A topological index reflects the physical, chemical and structural properties of a molecule, and its study has an important role in molecular topology, chemical graph theory and mathematical chemistry. It is a natural problem to…

Combinatorics · Mathematics 2022-07-08 Rui Song , Qiongxiang Huang

Elliptic Sombor and Euler Sombor indices are recently defined topological indices using Sombor index. Elliptic sombor index is defined as $ESO(G)=\sum_{uv\in E(G)}(d_u+ d_v)\sqrt{d^2_u+ d^2_v}$ and Euler Sombor index is defined as $EU(G)=…

Combinatorics · Mathematics 2024-06-25 B. Kirana , M. C. Shanmukha , A. Usha

Recently, based on elementary geometry, Gutman proposed several geometry-based invariants (i.e., $SO$, $SO_{1}$, $SO_{2}$, $SO_{3}$, $SO_{4}$, $SO_{5}$, $SO_{6}$). The Sombor index was defined as $SO(G)=\sum\limits_{uv\in…

Combinatorics · Mathematics 2023-07-19 Hechao Liu

Let $G$ be a graph with vertex set $V(G)$ and edge set $E(G)$. The Sombor and reduced Sombor indices of $G$ are defined as $SO(G)=\sum_{uv\in E(G)}\sqrt{deg_G(u)^2+deg_G(v)^2}$ and $SO_{red}(G)=\sum_{uv\in…

Combinatorics · Mathematics 2021-04-01 Kinkar Chandra Das , Ali Ghalavand , Ali Reza Ashrafi

Topological indices play a significant role in mathematical chemistry. Given a graph $\mathcal{G}$ with vertex set $\mathcal{V}=\{1,2,\dots,n\}$ and edge set $\mathcal{E}$, let $d_i$ be the degree of node $i$. The degree-based topological…

Combinatorics · Mathematics 2023-10-09 Mingao Yuan

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…

Combinatorics · Mathematics 2025-12-16 Jasem Hamoud , Alexey Belov Yakovlevich , Muaadh Almahalebi , Duaa Abdullah

We study the Sombor index of trees with various degree restrictions. In addition to rediscovering that among all trees with a given degree sequence, the greedy tree minimises the Sombor index and the alternating greedy tree maximises it, we…

Combinatorics · Mathematics 2024-04-03 Eric O. D. Andriantiana , Valisoa R. M. Rakotonarivo

In this paper, we investigate the structural properties of trees and bipartite graphs through the lens of topological indices and combinatorial graph theory. We focus on the First and Second Hyper-Zagreb indices, $HM_1(G)$ and $HM_2(G)$,…

Combinatorics · Mathematics 2025-08-21 Jasem Hamoud

The Sombor index is one of the geometry-based descriptors, which was defined as $$SO(G)=\sum_{uv\in E(G)}\sqrt{d^{2}(u)+d^{2}(v)},$$ where $d(u)$ (resp. $d(v)$) denotes the degree of vertex $u$ (resp. $v$) in $G$. In this note, we determine…

Combinatorics · Mathematics 2022-08-25 Hechao Liu

We study a wide class of topological free-fermion systems on a hypercubic lattice in spatial dimensions $d\ge 1$. When the Fermi level lies in a spectral gap or a mobility gap, the topological properties, e.g., the integral quantization of…

Mathematical Physics · Physics 2018-05-23 Hosho Katsura , Tohru Koma

We build on recent work of Yeats, Courtiel, and others involving connected chord diagrams. We first derive from a Hopf-algebraic foundation a class of tree-like functional equations and prove that they are solved by weighted generating…

Combinatorics · Mathematics 2021-04-07 Lukas Nabergall

We study a class of combinatorial objects that we call "decorated trees". These consist of vertices, arrows and edges, where each edge is decorated by two integers (one near each of its endpoints), each arrow is decorated by an integer, and…

Algebraic Geometry · Mathematics 2024-10-08 Pierrette Cassou-Noguès , Daniel Daigle

For a graph $G$ with edge set $E$, let $d(u)$ denote the degree of a vertex $u$ in $G$. The diminished Sombor (DSO) index of $G$ is defined as $DSO(G)=\sum_{uv\in E}\sqrt{(d(u))^2+(d(v))^2}(d(u)+d(v))^{-1}$. The cyclomatic number of a graph…

Combinatorics · Mathematics 2025-09-17 Abdulaziz Mutlaq Alotaibi , Abdulaziz M. Alanazi , Taher S. Hassan , Akbar Ali

The numerical values extracted from a graph that indicates its topology are called topological indices. A contemporary and efficient method is to compute a graph's topological indices using the graph polynomial that corresponds to it. This…

Discrete Mathematics · Computer Science 2026-02-18 Jayjit Barman , Shibsankar Das

Network science provides valuable insights across numerous disciplines including sociology, biology, neuroscience and engineering. A task of major practical importance in these application domains is inferring the network structure from…

Machine Learning · Computer Science 2019-05-01 Vassilis N. Ioannidis , Yanning Shen , Georgios B. Giannakis

The Elliptic Somber and Euler Somber indices are newly defined topological indices based on the Somber index. Our paper presents calculations of the upper and lower bounds of these indices for the join and corona product of arbitrary…

Combinatorics · Mathematics 2025-02-11 Bishal Sonar , Ravi Srivastava

We consider random graphs with a given degree sequence and show, under weak technical conditions, asymptotic normality of the number of components isomorphic to a given tree, first for the random multigraph given by the configuration model…

Probability · Mathematics 2019-02-01 Svante Janson

A semiregular tree is a tree where all non-pendant vertices have the same degree. Belardo et al. (MATCH Commun. Math. Chem. 61(2), pp. 503-515, 2009) have shown that among all semiregular trees with a fixed order and degree, a graph with…

Combinatorics · Mathematics 2009-06-09 Tuerker Biyikoglu , Josef Leydold

We note here that the problem of determining extremal values of Sombor index for trees with a given degree sequence fits within the framework of results by Hua Wang from [Cent. Eur. J. Math. 12 (2014) 1656-1663], implying that the greedy…

Combinatorics · Mathematics 2024-05-20 Ivan Damnjanović , Marko Milošević , Dragan Stevanović