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The geometry of the moduli space of stable spin curves is studied, with emphasis on its combinatorial properties. In this context, the standard graph theoretic framework is not just a book-keeping device: some purely combinatorial results…

Algebraic Geometry · Mathematics 2007-05-23 Lucia Caporaso , Cinzia Casagrande

The classical spectral Tur\'{a}n problem is to determine the maximum spectral radius of an $F$-free graph of order $n$. This paper extends this framework to signed graphs. Let $\mathcal{C}_r^-$ be the set of all unbalanced signed graphs…

Combinatorics · Mathematics 2025-12-09 Dan Li , Mingsong Qin

A \emph{Fibonacci cordial labeling} of a graph \( G \) is an injective function \( f: V(G) \rightarrow \{F_0, F_1, \dots, F_n\} \), where \( F_i \) denotes the \( i^{\text{th}} \) Fibonacci number, such that the induced edge labeling \(…

Combinatorics · Mathematics 2025-09-03 Sarbari Mitra , Soumya Bhoumik

This papers focuses on the average order of dominating sets of a graph. We find the extremal graphs for the maximum and minimum value over all graphs on $n$ vertices, while for trees we prove that the star minimizes the average order of…

Combinatorics · Mathematics 2020-08-18 Iain Beaton , Jason I. Brown

We consider the Tur\'an problems of $2$-edge-colored graphs. A $2$-edge-colored graph $H=(V, E_r, E_b)$ is a triple consisting of the vertex set $V$, the set of red edges $E_r$ and the set of blue edges $E_b$ with $E_r$ and $E_b$ do not…

Combinatorics · Mathematics 2020-12-14 Shuliang Bai , Linyuan Lu

The Alon-Tarsi number of a polynomial is a parameter related to the exponents of its monomials. For graphs, their Alon-Tarsi number is the Alon-Tarsi number of their graph polynomials. As such, it provides an upper bound on their choice and…

Combinatorics · Mathematics 2024-04-16 S. Prajnanaswaroopa

In 1952, Dirac proved that every $2$-connected $n$-vertex graph with the minimum degree $k+1$ contains a cycle of length at least $\min\{n, 2(k+1)\}$. Here we obtain a stability version of this result by characterizing those graphs with…

Combinatorics · Mathematics 2022-08-04 Xiutao Zhu , Ervin Győri , Zhen He , Zequn Lv , Nika Salia , Chuanqi Xiao

An ordered graph $H$ is a simple graph with a linear order on its vertex set. The corresponding Tur\'an problem, first studied by Pach and Tardos, asks for the maximum number $\text{ex}_<(n,H)$ of edges in an ordered graph on $n$ vertices…

Combinatorics · Mathematics 2017-11-22 Dániel Korándi , Gábor Tardos , István Tomon , Craig Weidert

An $r$-graph is an $r$-uniform hypergraph tree (or $r$-tree) if its edges can be ordered as $E_1,\ldots, E_m$ such that $\forall i>1 \, \exists \alpha(i)<i$ such that $E_i\cap (\bigcup_{j=1}^{i-1} E_j)\subseteq E_{\alpha(i)}$. The Tur\'an…

Combinatorics · Mathematics 2015-05-14 Zoltán Füredi , Tao Jiang

Graph convolutional neural networks (GCNNs) have emerged as powerful tools for analyzing graph-structured data, achieving remarkable success across diverse applications. However, the theoretical understanding of the stability of these…

Machine Learning · Computer Science 2025-10-28 Ning Zhang , Henry Kenlay , Li Zhang , Mihai Cucuringu , Xiaowen Dong

The Tur\'an number $\text{ex}(n,H)$ of a graph $H$ is the maximal number of edges in an $H$-free graph on $n$ vertices. In $1983$ Chung and Erd\H{o}s asked which graphs $H$ with $e$ edges minimize $\text{ex}(n,H)$. They resolved this…

Combinatorics · Mathematics 2023-06-22 Matija Bucić , Nemanja Draganić , Benny Sudakov

The stability number of a forbidden family measures how many different structures are needed to approximate all near-extremal constructions avoiding it. An infinite stability number means that no finite list of structures suffices. We…

Combinatorics · Mathematics 2026-05-22 Heng Li , Xizhi Liu

Turing patterns on unbounded domains have been widely studied in systems of reaction-diffusion equations. However, up to now, they have not been studied for systems of conservation laws. Here, we (i) derive conditions for Turing instability…

Analysis of PDEs · Mathematics 2018-01-17 Blake Barker , Soyeun Jung , Kevin Zumbrun

Let \( \mathcal{F} \) be a family of graphs. The generalized Tur\'an number \( \operatorname{ex}(n, K_r, \mathcal{F}) \) is the maximum number of $K_r$ in an \( n \)-vertex graph that does not contain any member of \( \mathcal{F} \) as a…

Combinatorics · Mathematics 2025-03-18 Yongchun Lu , Liying Kang , Yisai Xue

The generalized Tur\'an number $\mathrm{ex}(n,H,F)$ is the maximum number of copies of $H$ in $n$-vertex $F$-free graphs. We consider the case where $\chi(H)<\chi(F)$. There are several exact results on $\mathrm{ex}(n,H,F)$ when the…

Combinatorics · Mathematics 2022-09-09 Dániel Gerbner

Given a family $\mathcal{F}$ of $r$-graphs, the Tur\'{a}n number of $\mathcal{F}$ for a given positive integer $N$, denoted by $ex(N,\mathcal{F})$, is the maximum number of edges of an $r$-graph on $N$ vertices that does not contain any…

Combinatorics · Mathematics 2016-12-30 L. Maherani , M. Shahsiah

In this article, we study finite dynamical systems defined over graphs, where the functions are applied asynchronously. Our goal is to quantify and understand stability of the dynamics with respect to the update sequence, and to relate this…

Dynamical Systems · Mathematics 2009-09-10 Matthew Macauley , Henning S. Mortveit

Tur\'an's Theorem says that an extremal $K_{r+1}$-free graph is $r$-partite. The Stability Theorem of Erd\H{o}s and Simonovits shows that if a $K_{r+1}$-free graph with $n$ vertices has close to the maximal $t_r(n)$ edges, then it is close…

Combinatorics · Mathematics 2021-12-28 Dániel Korándi , Alexander Roberts , Alex Scott

The atom-bond connectivity (ABC) index is a degree-based topological index. It was introduced due to its applications in modeling the properties of certain molecular structures and has been since extensively studied. In this note, we…

Combinatorics · Mathematics 2016-08-26 Xiu-Mei Zhang , Yu Yang , Hua Wang , Xiao-Dong Zhang

The Tur\'an number of a graph $H$, denoted by $ex(n,H)$, is the maximum number of edges in any graph on $n$ vertices containing no $H$ as a subgraph. A linear (star) forest is a forest consisting of paths (stars). A path-star forest $F$ is…

Combinatorics · Mathematics 2024-12-11 Xiaona Fang , Yaojun Chen , Lihua You