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The aim of these notes is to introduce the intuition motivating the notion of a "complicial set", a simplicial set with certain marked "thin" simplices that witness a composition relation between the simplices on their boundary. By varying…

Category Theory · Mathematics 2016-10-24 Emily Riehl

Simplicial complexes are higher-order combinatorial structures which have been used to represent real-world complex systems. In this paper, we concentrate on the local patterns in simplicial complexes called simplets, a generalization of…

Social and Information Networks · Computer Science 2023-04-26 Hyunju Kim , Jihoon Ko , Fanchen Bu , Kijung Shin

We discuss $\pmb{SC}_*$, a simplicial homotopy model of $K(Z,2)$ constructed from circular permutations. In any dimension, the number of simplices in the model is finite. The complex $\pmb{SC}_*$ naturally manifests as a simplicial set…

Algebraic Topology · Mathematics 2024-08-20 Nikolai Mnëv

Much of the homotopical and homological structure of the categories of chain complexes and topological spaces can be deduced from the existence and properties of the 'simple' functors Tot : {double chain complexes} -> {chain complexes} and…

Algebraic Geometry · Mathematics 2008-04-15 Beatriz Rodriguez Gonzalez

We prove that the simplicial cocommutative coalgebra of singular chains on a connected topological space determines the homotopy type rationally and one prime at a time, without imposing any restriction on the fundamental group. In…

Algebraic Topology · Mathematics 2021-10-08 Manuel Rivera , Felix Wierstra , Mahmoud Zeinalian

This paper describes the homology of various simplicial complexes associated to set families from combinatorial number theory, including primitive sets, pairwise coprime sets, product-free sets, and coprime-free sets. We present a condition…

Combinatorics · Mathematics 2024-07-08 Marcel K. Goh , Jonah Saks

We construct new geometric realizations of simplicial and pre-simplicial sets where the standard $n$-simplex, viewed as the space of probability measures on $n+1$ elements, is replaced by the space of $(n+1)$-valued random variables, with…

Algebraic Topology · Mathematics 2022-10-04 Ivan Marin

Higher inductive types are a class of type-forming rules, introduced to provide basic (and not-so-basic) homotopy-theoretic constructions in a type-theoretic style. They have proven very fruitful for the "synthetic" development of homotopy…

Logic · Mathematics 2020-07-08 Peter LeFanu Lumsdaine , Mike Shulman

We verify that for a finite simplicial complex $X$ and for piecewise linear loops on $X$, the "thin" loop space is a topological group of the same homotopy type as the space of continuous loops. This turns out not to be the case for the…

Algebraic Topology · Mathematics 2019-09-26 Moncef Ghazel , Sadok Kallel

We introduce a new homology theory of quandles, called simplicial quandle homology, which is quite different from quandle homology developed by Carter et al. We construct a homomorphism from a quandle homology group to a simplicial quandle…

Geometric Topology · Mathematics 2015-03-17 Ayumu Inoue , Yuichi Kabaya

The theory of shellable simplicial complexes brings together combinatorics, algebra, and topology in a remarkable way. Initially introduced by Alder for $q$-simplicial complexes, recent work of Ghorpade, Pratihar, and Randrianarisoa extends…

We give an affirmative answer to the following question: Is any Borel subset of a Cantor set $\textbf{ C}$ a sum of a countable number of pairwise disjoint $h$-homogeneous subspaces that are closed in $X$? It follows that every Borel set $X…

Logic · Mathematics 2011-02-17 Alexey Ostrovsky

Let X be a Zariski open subset of a compact Kaehler manifold. In this paper, we study the set $\Sigma^k(X)$ of one dimensional local systems on X with nonvanishing kth cohomology. We show that under certain conditions (X compact, X has a…

alg-geom · Mathematics 2008-02-03 Donu Arapura

We prove a conjecture of Bahri, Bendersky, Cohen and Gitler: if K is a shifted simplicial complex on n vertices, X_1,..., X_n are spaces and CX_i is the cone on X_i, then the polyhedral product determined by K and the pairs (CX_i,X_i) is…

Algebraic Topology · Mathematics 2011-10-21 Jelena Grbic , Stephen Theriault

We consider a certain class of simplicial complexes which includes the independence complexes of forests. We show that if a simplicial complex $K$ belongs to this class, then the polyhedral join $\mathcal{Z}^*_{K}(\underline{X}, \emptyset)$…

Combinatorics · Mathematics 2023-03-22 Kengo Okura

Given a compact metric space $X$, we associate to it an inverse sequence of finite $T_0$ topological spaces. The inverse limit of this inverse sequence contains a homeomorphic copy of $X$ that is a strong deformation retract. We provide a…

Geometric Topology · Mathematics 2022-03-14 Pedro J. Chocano , Manuel A. Morón , Francisco R. Ruiz del Portal

We find boundaries of Borel-Serre compactifications of locally symmetric spaces, for which any filling is incompressible. We prove this result by showing that these boundaries have small singular models and using these models to obstruct…

Geometric Topology · Mathematics 2017-01-03 Grigori Avramidi

We study the category pro-SSet of pro-simplicial sets, which arises in etale homotopy theory, shape theory, and pro-finite completion. We establish a model structure on pro-SSet so that it is possible to do homotopy theory in this category.…

Algebraic Topology · Mathematics 2007-05-23 Daniel C. Isaksen

As observed recently by various people the topos $\mathbf{sSet}$ of simplicial sets appears as essential subtopos of a topos $\mathbf{cSet}$ of cubical sets, namely presheaves over the category $\mathbf{FL}$ of finite lattices and monotone…

Category Theory · Mathematics 2021-03-15 Thomas Streicher , Jonathan Weinberger

Let $C_\bullet$ be a simplicial object in the category $Cat$ of small categories. For a field $k$, taking the Grothendieck groups of isomorphism classes of $kC_n$-modules gives rise to a cochain complex, whose cohomology, which we refer to…

Representation Theory · Mathematics 2026-04-23 Markus Klemetti , Ran Levi , Henri Riihimaki , Daniel Solch