Representability and boxicity of simplicial complexes
| Autor: | Alan Lew |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Mathematics::Combinatorics
Dimension (graph theory) Regular polygon Theoretical Computer Science Vertex (geometry) Combinatorics Simplicial complex Computational Theory and Mathematics Intersection Computer Science::Discrete Mathematics FOS: Mathematics Discrete Mathematics and Combinatorics Mathematics - Combinatorics Geometry and Topology Combinatorics (math.CO) Boxicity Mathematics |
| Popis: | Let $X$ be a simplicial complex on vertex set $V$. We say that $X$ is $d$-representable if it is isomorphic to the nerve of a family of convex sets in $\mathbb{R}^d$. We define the $d$-boxicity of $X$ as the minimal $k$ such that $X$ can be written as the intersection of $k$ $d$-representable simplicial complexes. This generalizes the notion of boxicity of a graph, defined by Roberts. A missing face of $X$ is a set $\tau\subset V$ such that $\tau\notin X$ but $\sigma\in X$ for any $\sigma\subsetneq \tau$. We prove that the $d$-boxicity of a simplicial complex on $n$ vertices without missing faces of dimension larger than $d$ is at most $\left\lfloor\frac{1}{d+1}\binom{n}{d}\right\rfloor$. The bound is sharp: the $d$-boxicity of a simplicial complex whose set of missing faces form a Steiner $(d,d+1,n)$-system is exactly $\frac{1}{d+1}\binom{n}{d}$. |
| Databáze: | OpenAIRE |
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