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This paper gives an introduction to the homotopy theory of quasi-categories. Weak equivalences between quasi-categories are characterized as maps which induce equivalences on a naturally defined system of groupoids. These groupoids…

Category Theory · Mathematics 2019-09-19 J. F. Jardine

We address the homotopy theory of 2-crossed modules of commutative algebras, which are equivalent to simplicial commutative algebras with Moore complex of length two. In particular, we construct for maps of 2-crossed modules a homotopy…

Category Theory · Mathematics 2017-05-23 İ. İlker Akça , Kadir Emir , João Faria Martins

Using Lipschitz distance on Outer space we give another proof of the train track theorem.

Group Theory · Mathematics 2011-02-03 Mladen Bestvina

We investigate properties which ensure that a given finite graph is the commuting graph of a group or semigroup. We show that all graphs on at least two vertices such that no vertex is adjacent to all other vertices is the commuting graph…

Group Theory · Mathematics 2016-05-18 Michael Giudici , Bojan Kuzma

We present parity conditions under which a toy rail network is one-way, i.e., whether a direction can be assigned across the network so that all train journeys are completely consistent with it or completely consistent with its opposite. We…

Combinatorics · Mathematics 2025-09-16 Dai Akita , Daniel Thorsten Schenz

I define a "group graph" which encodes the symmetry in a dynamical process on a network. Group graphs extend signed networks, where links are labelled with plus or minus one, by allowing link labels from any group and generalising the…

Physics and Society · Physics 2025-07-18 Tim S. Evans

In [S. Basu, A. Gabrielov, N. Vorobjov, Semi-monotone sets. arXiv:1004.5047v2 (2011)] we defined semi-monotone sets, as open bounded sets, definable in an o-minimal structure over the reals, and having connected intersections with all…

Logic · Mathematics 2013-04-10 Saugata Basu , Andrei Gabrielov , Nicolai Vorobjov

In this paper, we develop a $\times$-homotopy fundamental groupoid for graphs, and show a functorial relationship to the 2-category of graphs. We further explore the fundamental groupoid of graph products and develop a groupoid product…

Combinatorics · Mathematics 2020-07-14 Tien Chih , Laura Scull

We establish an equivalence of homotopy theories between symmetric monoidal bicategories and connective spectra. For this, we develop the theory of $\Gamma$-objects in 2-categories. In the course of the proof we establish strictfication…

Algebraic Topology · Mathematics 2017-12-07 Nick Gurski , Niles Johnson , Angélica M. Osorno

Assume that there is a free group action of automorphisms on a bipartite graph. If there is a perfect matching on the factor graph, then obviously there is a perfect matching on the graph. Surprisingly, the reversed is also true for…

Group Theory · Mathematics 2016-07-26 Jan Fricke

We discuss topological versions of the closed graph theorem, where continuity is inferred from near continuity in tandem with suitable conditions on source or target spaces. We seek internal characterizations of spaces satisfying a closed…

General Topology · Mathematics 2024-04-05 Dominikus Noll

For a locally finite, connected graph $\Gamma$, let $\operatorname{Map}(\Gamma)$ denote the group of proper homotopy equivalences of $\Gamma$ up to proper homotopy. Excluding sporadic cases, we show $\operatorname{Aut}(S(M_\Gamma)) \cong…

Geometric Topology · Mathematics 2024-10-10 Thomas Hill , Michael C. Kopreski , Rebecca Rechkin , George Shaji , Brian Udall

We consider word maps and word maps with constants on a simple algebraic group. We present results on the images of such maps, in particular, we prove a theorem on the dominance of general word maps with constants, which can be viewed as an…

Group Theory · Mathematics 2018-01-03 Nikolai Gordeev , Boris Kunyavskii , Eugene Plotkin

We describe the relation of $r$-similarity and finite-order invariants on the homotopy set $[S^1,Y]=\pi_1(Y)$.

Algebraic Topology · Mathematics 2026-02-16 S. S. Podkorytov

The homotopy theory of gauge groups has received considerable attention in recent decades. In this work, we study the homotopy theory of gauge groups over some high dimensional manifolds. To be more specific, we study gauge groups of…

Algebraic Topology · Mathematics 2021-03-24 Ruizhi Huang

A concise discussion of the axiomatic approach to the concept of parallel transport is presented. Attention is drawn to a bijective map between the sets of connections and (axiomatically defined) parallel transports. The transports along…

Mathematical Physics · Physics 2007-11-01 Bozhidar Z. Iliev

Twisted diagrams are "diagrams" with components in different categories. Structure maps are defined using auxiliary data which consists of functors relating the various categories to each other. Prime examples of the construction are…

Algebraic Topology · Mathematics 2008-05-28 Thomas Huettemann , Oliver Roendigs

We relativise the Thomassen--Woess definition of accessibility in graphs, defining what it means for a graph to be accessible relative to a peripheral system. In the case of locally finite, quasi-transitive graphs, we characterise relative…

Combinatorics · Mathematics 2026-05-14 Joseph Paul MacManus

In this paper we develop homotopy theoretical methods for studying diagrams. In particular we explain how to construct homotopy colimits and limits in an arbitrary model category. The key concept we introduce is that of a model…

Algebraic Topology · Mathematics 2009-09-25 Wojciech Chacholski , Jerome Scherer

We defined a grid homology theory for spatial graphs. We showed that the skein exact sequence of singular knots can be extended to our grid homology for spatial graphs.

Geometric Topology · Mathematics 2021-09-29 Zipei Zhuang