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We consider a multi-parameter model for randomly constructing simplicial complexes. This model interpolates between random clique complexes and Linial-Meshulam random $k$-dimensional complexes, two models that have been extensively studied.…

Algebraic Topology · Mathematics 2015-06-04 Christopher F. Fowler

Several years ago Linial and Meshulam introduced a model called X_d(n,p) of random n-vertex d-dimensional simplicial complexes. The following question suggests itself very naturally: What is the threshold probability p=p(n) at which the…

Combinatorics · Mathematics 2012-03-16 L. Aronshtam , N. Linial

Let Y be a random d-dimensional subcomplex of the (n-1)-dimensional simplex S obtained by starting with the full (d-1)-dimensional skeleton of S and then adding each d-simplex independently with probability p=c/n. We compute an explicit…

Combinatorics · Mathematics 2011-08-04 L. Aronshtam , N. Linial , T. Luczak , R. Meshulam

We consider a generalised model of a random simplicial complex, which arises from a random hypergraph. Our model is generated by taking the downward-closure of a non-uniform binomial random hypergraph, in which for each $k$, each set of…

Combinatorics · Mathematics 2020-11-06 Oliver Cooley , Nicola Del Giudice , Mihyun Kang , Philipp Sprüssel

It is proved that fundamental groups of boolean representable simplicial complexes are free and the rank is determined by the number and nature of the connected components of their graph of flats for dimension $\geq 2$. In the case of…

Combinatorics · Mathematics 2015-10-20 Stuart Margolis , John Rhodes , Pedro V. Silva

We examine properties of random numerical semigroups under a probabilistic model inspired by the Erdos-Renyi model for random graphs. We provide a threshold function for cofiniteness, and bound the expected embedding dimension, genus, and…

Commutative Algebra · Mathematics 2017-10-25 Jesus De Loera , Christopher O'Neill , Dane Wilburne

We consider $k$-dimensional random simplicial complexes that are generated from the binomial random $(k+1)$-uniform hypergraph by taking the downward-closure, where $k\geq 2$. For each $1\leq j \leq k-1$, we determine when all cohomology…

Combinatorics · Mathematics 2018-06-13 Oliver Cooley , Nicola Del Giudice , Mihyun Kang , Philipp Sprüssel

Clique complexes of Erd\H{o}s-R\'{e}nyi random graphs with edge probability between $n^{-{1\over 3}}$ and $n^{-{1\over 2}}$ are shown to be aas not simply connected. This entails showing that a connected two dimensional simplicial complex…

Combinatorics · Mathematics 2013-02-19 Eric Babson

We study random simplicial complexes in the multi-parameter upper model. In this model simplices of various dimensions are taken randomly and independently, and our random simplicial complex $Y$ is then taken to be the minimal simplicial…

Algebraic Topology · Mathematics 2022-09-13 Michael Farber , Tahl Nowik

A Hamiltonian cycle in a graph is a spanning subgraph that is homeomorphic to a circle. With this in mind, it is natural to define a Hamiltonian d-sphere in a d-dimensional simplicial complex as a spanning subcomplex that is homeomorphic to…

Combinatorics · Mathematics 2018-09-26 Zur Luria , Ran J. Tessler

We consider simplicial complexes that are generated from the binomial random 3-uniform hypergraph by taking the downward-closure. We determine when this simplicial complex is homologically connected, meaning that its zero-th and first…

Combinatorics · Mathematics 2016-04-05 Oliver Cooley , Penny Haxell , Mihyun Kang , Philipp Sprüssel

We demonstrate the existence of minimal simplicial $n$-complexes which inevitably contain a nonsplittable two-component link formed by an $(n-1)$-sphere and an $n$-sphere in any embedding into $\mathbb{R}^{2n}$. This provides a…

Geometric Topology · Mathematics 2026-03-17 Ryo Nikkuni

The $m$-neighbor complex of a graph is the simplicial complex in which faces are sets of vertices with at least $m$ common neighbors. We consider these complexes for Erdos-Renyi random graphs and find that for certain explicit families of…

Combinatorics · Mathematics 2023-09-12 Eric Babson , Jan Spaliński

Let $L$ be a simplicial complex. In this paper, we study random sub-hypergraphs and random sub-complexes of $L$. By considering the minimal complex that a sub-hypergraph can be embedded in and the maximal complex that can be embedded in a…

Algebraic Topology · Mathematics 2022-07-14 Shiquan Ren , Chengyuan Wu , Jie Wu

The paper surveys recent progress in understanding geometric, topological and combinatorial properties of large simplicial complexes, focusing mainly on ampleness, connectivity and universality. In the first part of the paper we concentrate…

Combinatorics · Mathematics 2023-01-19 Michael Farber

Linial-Meshulam complex is a random simplicial complex on $n$ vertices with a complete $(d-1)$-dimensional skeleton and $d$-simplices occurring independently with probability p. Linial-Meshulam complex is one of the most studied…

Probability · Mathematics 2023-02-23 Kartick Adhikari , Kiran Kumar A. S. , Koushik Saha

We prove a topological rigidity result for simple, thick, hyperbolic P-manifolds of dimension 2: isomorphism of the fundamental groups implies homeomorphism of the P-manifolds. An immediate application is a diagram rigidity theorem for…

Group Theory · Mathematics 2007-05-23 J. -F. Lafont

Random shapes arise naturally in many contexts. The topological and geometric structure of such objects is interesting for its own sake, and also for applications. In physics, for example, such objects arise naturally in quantum gravity, in…

Combinatorics · Mathematics 2016-07-26 Matthew Kahle

For random graphs, the containment problem considers the probability that a binomial random graph $G(n,p)$ contains a given graph as a substructure. When asking for the graph as a topological minor, i.e., for a copy of a subdivision of the…

Combinatorics · Mathematics 2015-05-05 Anna Gundert , Uli Wagner

We study high dimensional expansion beyond simplicial complexes (posets) and focus on $q$-complexes which are complexes whose basic building blocks are linear spaces. We show that the complete $q$-complex (consists of all subspaces of a…

Combinatorics · Mathematics 2024-01-24 Ran Tessler , Elad Tzalik