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The total reciprocal edge-eccentricity is a novel graph invariant with vast potential in structure activity/property relationships. This graph invariant displays high discriminating power with respect to both biological activity and…

组合数学 · 数学 2015-08-25 Shuchao Li , Lifang Zhao

The sigma index in graph theory refers to a measure of the degree differences between vertices in a graph. The goal is to determine the graphs that have the maximum sigma index within certain classes of graphs. Abdo, Dimitrov, and Gutman…

综合数学 · 数学 2024-05-10 Jasem Hamoud , Artem Kurnosov

The early development of a zygote can be mathematically described by a developmental tree. To compare developmental trees of different species, we need to define distances on trees. If children cells after a division are not…

组合数学 · 数学 2022-06-08 Yue Wang

Optimal transport provides a metric which quantifies the dissimilarity between probability measures. For measures supported in discrete metric spaces, finding the optimal transport distance has cubic time complexity in the size of the…

机器学习 · 计算机科学 2024-01-30 Samantha Chen , Puoya Tabaghi , Yusu Wang

We study subgraphs that appear in large Ramsey graphs for a given graph $F$. The recent girth Ramsey theorem of the first two authors asserts that there are Ramsey graphs such that all small subgraphs are `forests of copies of $F$'…

组合数学 · 数学 2025-02-17 Christian Reiher , Vojtěch Rödl , Mathias Schacht

The subpath number of a graph G is defined as the total number of subpaths in G, and it is closely related to the number of subtrees, a well-studied topic in graph theory. This paper is a continuation of our previous paper [5], where we…

组合数学 · 数学 2025-03-05 Martin Knor , Jelena Sedlar , Riste Škrekovski , Yu Yang

The Steiner $k$-eccentricity of a vertex in graph $G$ is the maximum Steiner distance over all $k$-subsets containing the vertex. %Some general properties of the Steiner 3-eccentricity of trees are given. Let $\mathbb{T}_n$ be the set of…

组合数学 · 数学 2022-05-09 Xin Liu

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

There are many ways of measuring and modeling tail-dependence in random vectors: from the general framework of multivariate regular variation and the flexible class of max-stable vectors down to simple and concise summary measures like the…

概率论 · 数学 2022-12-05 Anja Janßen , Sebastian Neblung , Stilian Stoev

In a study on the structure--dependency of the total $\pi$-electron energy from 1972, Trinajsti\'c and one of the present authors have shown that it depends on the sums $\sum_{v\in V}d(v)^2$ and $\sum_{v\in V}d(v)^3$, where $d(v)$ is the…

离散数学 · 计算机科学 2015-09-21 Hosam Abdo , Darko Dimitrov , Ivan Gutman

Vertex-degree-based topological indices have recently gained a lot of attention from mathematical chemists. One such index that we focus on in this paper is called Sombor index. After its definition in late 2020, the Sombor index was…

组合数学 · 数学 2022-12-09 Mirza Redžić

In multivariate extreme value analysis, the nature of the extremal dependence between variables should be considered when selecting appropriate statistical models. Interest often lies with determining which subsets of variables can take…

统计方法学 · 统计学 2022-07-19 Emma S. Simpson , Jennifer L. Wadsworth , Jonathan A. Tawn

The vertex $k$-partiteness $v_k(G)$ of graph $G$ is defined as the fewest number of vertices whose deletion from $G$ yields a $k$-partite graph. In this paper, we introduce two concepts: monotonic decreasing topological index and monotonic…

组合数学 · 数学 2017-08-04 Fang Gao , Duo Duo Zhao , Xiao-Xin Li , Jia-Bao Liu

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

The Subtree Isomorphism problem asks whether a given tree is contained in another given tree. The problem is of fundamental importance and has been studied since the 1960s. For some variants, e.g., ordered trees, near-linear time algorithms…

计算复杂性 · 计算机科学 2015-10-16 Amir Abboud , Arturs Backurs , Thomas Dueholm Hansen , Virginia Vassilevska Williams , Or Zamir

The Wiener index of a graph is the sum of the distances between all pairs of vertices, it has been one of the main descriptors that correlate achemical compound's molecular graph with experimentally gathered data regarding the compound's…

组合数学 · 数学 2007-09-12 Hua Wang

The graph edit distance is used for comparing graphs in various domains. Due to its high computational complexity it is primarily approximated. Widely-used heuristics search for an optimal assignment of vertices based on the distance…

数据结构与算法 · 计算机科学 2023-12-08 Franka Bause , Christian Permann , Nils M. Kriege

We address here spanning tree problems on a graph with binary edge weights. For a general weighted graph the minimum spanning tree is solved in super-linear running time, even when the edges of the graph are pre-sorted. A related problem,…

数据结构与算法 · 计算机科学 2024-01-17 Dorit S. Hochbaum

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

We consider drawings of graphs in the plane in which vertices are assigned distinct points in the plane and edges are drawn as simple curves connecting the vertices and such that the edges intersect only at their common endpoints. There is…

计算几何 · 计算机科学 2022-03-17 Salman Parsa , Tim Ophelders