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Given a graph $G$ and a vertex $v\in V(G)$, a local complementation at $v$ on $G$ is an operation that replaces the induced graph on the neighborhood of $v$ by its complement. A graph $H$ is a vertex-minor if $H$ can be obtained from $G$ by…

Combinatorics · Mathematics 2026-05-06 Ting-Wei Chao , Zixuan Xu

We determine to within a constant factor the threshold for the property that two random k-uniform hypergraphs with edge probability p have an edge-disjoint packing into the same vertex set. More generally, we allow the hypergraphs to have…

Combinatorics · Mathematics 2016-03-01 Béla Bollobás , Svante Janson , Alex Scott

We study random subgraphs of the 2-dimensional Hamming graph H(2,n), which is the Cartesian product of two complete graphs on $n$ vertices. Let $p$ be the edge probability, and write $p=\frac{1+\vep}{2(n-1)}$ for some $\vep\in \R$. In Borgs…

Probability · Mathematics 2008-12-15 Remco van der Hofstad , Malwina J. Luczak

We consider two variants of the induced subgraph isomorphism problem for two independent binomial random graphs with constant edge-probabilities p_1,p_2. In particular, (i) we prove a sharp threshold result for the appearance of G_{n,p_1}…

Combinatorics · Mathematics 2025-07-24 Erlang Surya , Lutz Warnke , Emily Zhu

The maximum likelihood threshold of a graph is the smallest number of data points that guarantees that maximum likelihood estimates exist almost surely in the Gaussian graphical model associated to the graph. We show that this graph…

Combinatorics · Mathematics 2015-09-17 Elizabeth Gross , Seth Sullivant

For a graph $G$ and a parameter $k$, we call a vertex $k$-enabling if it belongs both to a clique of size $k$ and to an independent set of size $k$, and we call it $k$-excluding otherwise. Motivated by issues that arise in secret sharing…

Data Structures and Algorithms · Computer Science 2025-09-03 Uriel Feige , Ilia Pauzner

We prove that for every non-trivial hereditary family of graphs ${\cal P}$ and for every fixed $p \in (0,1)$, the maximum possible number of edges in a subgraph of the random graph $G(n,p)$ which belongs to ${\cal P}$ is, with high…

Combinatorics · Mathematics 2022-10-25 Noga Alon , Michael Krivelevich , Wojciech Samotij

In this letter we study the NP-complete vertex cover problem on finite connectivity random graphs. When the allowed size of the cover set is decreased, a discontinuous transition in solvability and typical-case complexity occurs. This…

Disordered Systems and Neural Networks · Physics 2009-10-31 Martin Weigt , Alexander K. Hartmann

We study the following combinatorial counting and sampling problems: can we efficiently sample from the Erd\H{o}s-R\'{e}nyi random graph $G(n,p)$ conditioned on triangle-freeness? Can we efficiently approximate the probability that $G(n,p)$…

Data Structures and Algorithms · Computer Science 2024-10-31 Matthew Jenssen , Will Perkins , Aditya Potukuchi , Michael Simkin

A graph $G=(V,E)$ is called $d$-rigid if, for a generic embedding of its vertices in $\mathbb{R}^d$, every edge-length preserving continuous motion of the vertices preserves the distances between all pairs of non-adjacent vertices as well.…

Combinatorics · Mathematics 2026-03-02 Michael Krivelevich , Alan Lew , Peleg Michaeli

The bandwidth theorem [Mathematische Annalen, 343(1):175--205, 2009] states that any $n$-vertex graph $G$ with minimum degree $\big(\tfrac{k-1}{k}+o(1)\big)n$ contains all $n$-vertex $k$-colourable graphs $H$ with bounded maximum degree and…

Combinatorics · Mathematics 2020-05-13 Peter Allen , Julia Böttcher , Julia Ehrenmüller , Anusch Taraz

Extremal properties of sparse graphs, randomly perturbed by the binomial random graph are considered. It is known that every $n$-vertex graph $G$ contains a complete minor of order $\Omega(n/\alpha(G))$. We prove that adding $\xi n$ random…

Combinatorics · Mathematics 2022-12-15 Elad Aigner-Horev , Dan Hefetz , Michael Krivelevich

We study the largest component of a random (multi)graph on n vertices with a given degree sequence. We let n tend to infinity. Then, under some regularity conditions on the degree sequences, we give conditions on the asymptotic shape of the…

Combinatorics · Mathematics 2007-07-13 Svante Janson , Malwina Luczak

Fix a graph $H$ and some $p\in (0,1)$, and let $X_H$ be the number of copies of $H$ in a random graph $G(n,p)$. Random variables of this form have been intensively studied since the foundational work of Erd\H{o}s and R\'{e}nyi. There has…

Combinatorics · Mathematics 2020-11-19 Jacob Fox , Matthew Kwan , Lisa Sauermann

A tessellation of a graph is a partition of its vertices into vertex disjoint cliques. A tessellation cover of a graph is a set of tessellations that covers all of its edges. The $t$-tessellability problem aims to decide whether there is a…

Discrete Mathematics · Computer Science 2021-06-24 A. Abreu , L. Cunha , T. Fernandes , C. de Figueiredo , L. Kowada , F. Marquezino , D. Posner , R. Portugal

Various simplicial complexes can be associated with a graph. Box complexes form an important families of such simplicial complexes and are especially useful for providing lower bounds on the chromatic number of the graph via some of their…

Combinatorics · Mathematics 2024-01-05 Hamid Reza Daneshpajouh , Frédéric Meunier

We determine the sharp threshold for the containment of all $n$-vertex trees of bounded degree in random geometric graphs with $n$ vertices. This provides a geometric counterpart of Montgomery's threshold result for binomial random graphs,…

Combinatorics · Mathematics 2025-05-23 Michael Anastos , Sahar Diskin , Dawid Ignasiak , Lyuben Lichev , Yetong Sha

The topological containment problem is known to be polynomial-time solvable for any fixed pattern graph $H$, but good characterisations have been found for only a handful of non-trivial pattern graphs. The complete graph on five vertices,…

Discrete Mathematics · Computer Science 2017-05-05 Rebecca Robinson , Graham Farr

A hypergraph can be obtained from a simplicial complex by deleting some non-maximal simplices. By [11], a hypergraph gives an associated simplicial complex. By [4], the embedded homology of a hypergraph is the homology of the infimum chain…

Algebraic Topology · Mathematics 2020-06-04 Shiquan Ren , Chong Wang , Chengyuan Wu , Jie Wu

We use probabilistic methods to find lower bounds on the maximum number, in a graph with domination number \gamma, of dominating sets of size \gamma. We find that we can randomly generate a graph that, w.h.p., is dominated by almost all…

Combinatorics · Mathematics 2013-08-15 Samuel Connolly , Zachary Gabor , Anant Godbole , Bill Kay