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We define homotopy-theoretic invariants of knots in prime 3-manifolds. Fix a knot J in a prime 3-manifold M. Call a knot K in M concordant to J if it cobounds a properly embedded annulus with J in MxI, and call K J-characteristic if there…

Geometric Topology · Mathematics 2011-11-01 Prudence Heck

A knot is a circle piecewise-linearly embedded into the 3-sphere. The topology of a knot is intimately related to that of its exterior, which is the complement of an open regular neighborhood of the knot. Knots are typically encoded by…

Geometric Topology · Mathematics 2023-03-20 Nathan M. Dunfield , Malik Obeidin , Cameron Gates Rudd

Two natural generalizations of knot theory are the study of spatially embedded graphs, and Kauffman's theory of virtual knots. In this paper we combine these approaches to begin the study of virtual spatial graphs.

Geometric Topology · Mathematics 2009-01-10 Thomas Fleming , Blake Mellor

We prove that every connected graph can be realized as the cut locus of some point on some Riemannian surface $S$ which, in some cases, has constant curvature. We study the stability of such realizations, and their generic behavior.

Differential Geometry · Mathematics 2016-08-14 Jin-ichi Itoh , Costin Vîlcu

We introduce new sufficient conditions for intrinsic knotting and linking. A graph on n vertices with at least 4n-9 edges is intrinsically linked. A graph on n vertices with at least 5n-14 edges is intrinsically knotted. We also classify…

Geometric Topology · Mathematics 2007-05-23 J. Campbell , T. W. Mattman , R. Ottman , J. Pyzer , M. Rodrigues , S. Williams

We classify nonnegatively curved simply connected 4-manifolds with circle symmetry up to equivariant diffeomorphisms. The main problem is rule out knotted curves in the singular set of the orbit space. As an extension of this work we…

Differential Geometry · Mathematics 2016-01-20 Karsten Grove , Burkhard Wilking

Contraction of an edge merges its end points into a new vertex which is adjacent to each neighbor of the end points of the edge. An edge in a $k$-connected graph is {\em contractible} if its contraction does not result in a graph of lower…

Discrete Mathematics · Computer Science 2009-02-10 N. S. Narayanaswamy , N. Sadagopan , Apoorve Dubey

We initiate the study of classical knots through the homotopy class of the n-th evaluation map of the knot, which is the induced map on the compactified n-point configuration space. Sending a knot to its n-th evaluation map realizes the…

Geometric Topology · Mathematics 2007-05-23 Ryan Budney , James Conant , Kevin P. Scannell , Dev Sinha

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

Tutte's embedding theorem states that every 3-connected graph without a $K_5$ or $K_{3,3}$ minor (i.e. a planar graph) is embedded in the plane if the outer face is in convex position and the interior vertices are convex combinations of…

Computational Geometry · Computer Science 2023-03-28 Marc Alexa

In this article, we demonstrate methods for the local removal and modification of complex tangents to embeddings of $S^3$ into $\mathbb{C}^3$. In particular, given any embedding of $S^3$ and a neighborhood of the complex tangents of the…

Complex Variables · Mathematics 2015-06-26 Ali M. Elgindi

The concordance group of knots in the three-sphere contains an infinite subgroup generated by elements of order two, each one of which is represented by a knot K with the property that for every n > 0, the n-fold cyclic cover of S^3…

Geometric Topology · Mathematics 2024-03-27 Charles Livingston

A locally connected spanning tree of a graph $G$ is a spanning tree $T$ of $G$ such that the set of all neighbors of $v$ in $T$ induces a connected subgraph of $G$ for every $v\in V(G)$. The purpose of this paper is to give linear-time…

Data Structures and Algorithms · Computer Science 2007-05-23 Ching-Chi Lin , Gerard J. Chang , Gen-Huey Chen

We study the spaces of embeddings $S^m\hookrightarrow R^n$ and those of long embeddings $R^m\hookrightarrow R^n$, i.e. embeddings of a fixed behavior outside a compact set. More precisely we look at the homotopy fiber of the inclusion of…

Algebraic Topology · Mathematics 2021-03-25 Victor Turchin , Thomas Willwacher

An embedding of a graph in $3$-space is linkless if for every two disjoint cycles there exists an embedded ball that contains one of the cycles and is disjoint from the other. We prove that every bipartite linklessly embeddable (simple)…

Combinatorics · Mathematics 2020-01-01 Rose McCarty , Robin Thomas

This paper is intended as an introductory survey of a newly emerging field: a topological approach to the study of locally finite graphs that crucially incorporates their ends. Topological arcs and circles, which may pass through ends,…

Combinatorics · Mathematics 2012-07-11 Reinhard Diestel

Computational topology is an area that revisits topological problems from an algorithmic point of view, and develops topological tools for improved algorithms. We survey results in computational topology that are concerned with graphs drawn…

Computational Geometry · Computer Science 2017-09-06 Éric Colin de Verdière

In this article, we study the knots realized by periodic orbits of R-covered Anosov flows in compact 3-manifolds. We show that if two orbits are freely homotopic then in fact they are isotopic. We show that lifts of periodic orbits to the…

Dynamical Systems · Mathematics 2015-06-23 Thomas Barthelmé , Sergio R. Fenley

Topological drawings are natural representations of graphs in the plane, where vertices are represented by points, and edges by curves connecting the points. Topological drawings of complete graphs and of complete bipartite graphs have been…

Computational Geometry · Computer Science 2017-02-10 Jean Cardinal , Stefan Felsner

We show that a smooth embedding of a closed 3-manifold in S^3 x R can be isotoped so that every generic level divides S^3 x t into two handlebodies (i.e., is Heegaard) provided the original embedding has a unique local maximum with respect…

Geometric Topology · Mathematics 2014-04-23 Ian Agol , Michael H. Freedman