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Let $G_1,\dots, G_m$ be independent identically distributed random subgraphs of the complete graph ${\cal K}_n$. We analyse the threshold behaviour of the strength of connectedness of the union $\cup_{i=1}^mG_i$ defined on the vertex set of…

Combinatorics · Mathematics 2026-02-12 Mindaugas Bloznelis

Let $\mathcal{F}$ be a family of $r$-graphs. An $r$-graph $G$ is called $\mathcal{F}$-saturated if it does not contain any members of $\mathcal{F}$ but adding any edge creates a copy of some $r$-graph in $\mathcal{F}$. The saturation number…

Combinatorics · Mathematics 2020-08-28 Natalie C. Behague

This work considers the robustness of uncertain consensus networks. The first set of results studies the stability properties of consensus networks with negative edge weights. We show that if either the negative weight edges form a cut in…

Optimization and Control · Mathematics 2015-03-03 Daniel Zelazo , Mathias Bürger

A non-empty set $S\subseteq V (G)$ of the simple graph $G=(V(G),E(G))$ is an independent dominating set of $G$ if every vertex not in $S$ is adjacent with some vertex in $S$ and the vertices of $S$ are pairwise non-adjacent. The independent…

Combinatorics · Mathematics 2023-11-06 Saeid Alikhani , Mazharodin Mehraban , Alexei Zakharov , Hamidreza Golmohammadi

We consider the following generalization of the seminal Erd\H{o}s-Ko-Rado theorem, due to Frankl. For some k>=2, let F be a k-wise intersecting family of r-subsets of an n element set X, i.e. for any k sets F1,...,Fk in F, their…

Combinatorics · Mathematics 2013-04-03 Vikram Kamat

The irregularity strength of a graph $G$, $s(G)$, is the least $k$ admitting a $\{1,2,\ldots,k\}$-weighting of the edges of $G$ assuring distinct weighted degrees of all vertices, or equivalently the least possible maximal edge multiplicity…

Combinatorics · Mathematics 2019-12-18 Jakub Przybyło

In this article we study the expanding properties of random perturbations of contracting Lorenz maps satisfying the summability condition of exponent 1. Under general conditions on the maps and perturbation types, we prove stochastic…

Dynamical Systems · Mathematics 2026-04-10 Haoyang Ji

Erd\H{o}s-Ko-Rado (EKR) type theorems yield upper bounds on the sizes of families of sets, subject to various intersection requirements on the sets in the family. Stability versions of such theorems assert that if the size of a family is…

Combinatorics · Mathematics 2018-05-28 David Ellis , Nathan Keller , Noam Lifshitz

In this paper, we consider saturation problems related to the celebrated Erd\H{o}s--Szekeres convex polygon problem. For each $n \ge 7$, we construct a planar point set of size $(7/8) \cdot 2^{n-2}$ which is saturated for convex $n$-gons.…

Combinatorics · Mathematics 2025-10-08 Gábor Damásdi , Zichao Dong , Manfred Scheucher , Ji Zeng

Consider the normalized adjacency matrices of random $d$-regular graphs on $N$ vertices with fixed degree $d\geq 3$, and denote the eigenvalues as $\lambda_1=d/\sqrt{d-1}\geq \lambda_2\geq\lambda_3\cdots\geq \lambda_N$. We prove that the…

Probability · Mathematics 2024-05-21 Jiaoyang Huang , Theo McKenzie , Horng-Tzer Yau

Let $k \geq 2$ be an integer. Kouider and Lonc proved that the vertex set of every graph $G$ with $n \geq n_0(k)$ vertices and minimum degree at least $n/k$ can be covered by $k - 1$ cycles. Our main result states that for every $\alpha >…

Combinatorics · Mathematics 2021-11-18 Frank Mousset , Nemanja Škorić , Miloš Trujić

We establish a strong, geometric lower bound on the (sequential) topological complexity of the unordered configuration spaces of a general graph. As an application, we show that, for most graphs, the topological complexity eventually…

Algebraic Topology · Mathematics 2026-02-05 Ben Knudsen

We investigate the \textit{edge group irregularity strength} ($es_g(G)$) of graphs, i.e. the smallest value of $s$ such that taking any Abelian group $\mathcal{G}$ of order $s$, there exists a function $f:V(G)\rightarrow \mathcal{G}$ such…

Combinatorics · Mathematics 2018-08-31 Marcin Anholcer , Sylwia Cichacz

In this paper we introduce a new way of measuring the robustness of Erd\H{o}s--Ko--Rado (EKR) Theorems on permutation groups. EKR-type results can be viewed as results about the independence numbers of certain corresponding graphs, namely…

Combinatorics · Mathematics 2025-02-21 Karen Gunderson , Karen Meagher , Joy Morris , Venkata Raghu Tej Pantangi , Mahsa N Shirazi

We call an edge-colored graph rainbow if all of its edges receive distinct colors. An edge-colored graph $\Gamma$ is called $H$-rainbow saturated if $\Gamma$ does not contain a rainbow copy of $H$ and adding an edge of any color to $\Gamma$…

Combinatorics · Mathematics 2024-03-20 Debsoumya Chakraborti , Kevin Hendrey , Ben Lund , Casey Tompkins

We prove that the property of containing a $k$-regular subgraph in the random graph model $G(n,p)$ has a sharp threshold for $k\ge3$. We also show how to use similar methods to obtain an easy prove for the (known fact of) sharpness of…

Probability · Mathematics 2013-10-22 Shoham Letzter

We introduce weak oddness $\omega_{\textrm w}$, a new measure of uncolourability of cubic graphs, defined as the least number of odd components in an even factor. For every bridgeless cubic graph $G$, $\rho(G)\le\omega_{\textrm…

Discrete Mathematics · Computer Science 2016-02-10 Robert Lukoťka , Ján Mazák

If K is an odd-dimensional flag closed manifold, flag generalized homology sphere or a more general flag weak pseudomanifold with sufficiently many vertices, then the maximal number of edges in K is achieved by the balanced join of cycles.…

Combinatorics · Mathematics 2013-03-25 Michal Adamaszek

A graph $ G $ is said to be $ (H;k) $-vertex stable if $ G $ contains a~subgraph isomorphic to $ H $ even after removing any $ k $ of its vertices alongside with their incident edges. We will denote by $ \text{stab}(H;k) $ the minimum size…

Combinatorics · Mathematics 2021-06-16 Artur Kuźnar

Stability and dependence are model-theoretic notions that have recently proved highly effective in the study of structural and algorithmic properties of hereditary graph classes, and are considered key notions for generalizing to hereditary…

Combinatorics · Mathematics 2026-04-02 H. Buffière , E. Kim , P. Ossona de Mendez