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The Heegaard genus is a fundamental invariant of 3-manifolds. However, computing the Heegaard genus of a triangulated 3-manifold is NP-hard, and while algorithms exist, little work has been done in making such an algorithm efficient and…

Geometric Topology · Mathematics 2024-03-19 Benjamin A. Burton , Finn Thompson

We make use of the 3D nature of knots and links to find savings in computational complexity when computing knot invariants such as the linking number and, in general, most finite type invariants. These savings are achieved in comparison…

Geometric Topology · Mathematics 2024-01-15 Dror Bar-Natan , Itai Bar-Natan , Iva Halacheva , Nancy Scherich

We study numerical computation of conformal invariants of domains in the complex plane. In particular, we provide an algorithm for computing the conformal capacity of a condenser. The algorithm applies for wide kind of geometries: domains…

Complex Variables · Mathematics 2020-08-19 Mohamed M S Nasser , Matti Vuorinen

Knotted molecules occur naturally and are designed by scientists to gain special biological and material properties. Understanding and utilizing knotting require efficient methods to recognize and generate knotted structures, which are…

Computational Physics · Physics 2025-01-23 Zhiyu Zhang , Yongjian Zhu , Liang Dai

In this note we give concise formulas, which lead to a simple and fast computer program that computes a powerful knot invariant. This invariant $\rho_1$ is not new, yet our formulas are by far the simplest and fastest: given a knot we write…

Geometric Topology · Mathematics 2024-04-16 Dror Bar-Natan , Roland van der Veen

In this paper we summarise the work discussed in Ref. [1] and [2] (q-alg/9505003), in which we introduced a method helpful in solving the problem of knot classification. We also present results obtained since then.

q-alg · Mathematics 2008-02-03 Charilaos Aneziris

We explore the application of automated reasoning techniques to unknot detection, a classical problem of computational topology. We adopt a two-pronged experimental approach, using a theorem prover to try to establish a positive result…

Logic in Computer Science · Computer Science 2014-05-19 Andrew Fish , Alexei Lisitsa

The transient number of a knot K, denoted tr(K), is the minimal number of simple arcs that have to be attached to K, in order that K can be homotoped to a trivial knot in a regular neighborhood of the union of K and the arcs. We give a…

Geometric Topology · Mathematics 2024-11-27 Mario Eudave-Muñoz , Joan Carlos Segura Aguilar

We use technology from sutured manifold theory and the theory of Heegaard splittings to relate genus reducing crossing changes on knots in S^3 to twists on surfaces arising in circular Heegaard splittings for knot complements. In a separate…

Geometric Topology · Mathematics 2012-10-23 Alexander Coward

We define and compare several natural ways to compute the bridge number of a knot diagram. We study bridge numbers of crossing number minimizing diagrams, as well as the behavior of diagrammatic bridge numbers under the connected sum…

Geometric Topology · Mathematics 2021-07-09 Ryan Blair , Alexandra A. Kjuchukova , Makoto Ozawa

Let $P$ be a set of $n$ points in the plane. A crossing-free structure on $P$ is a plane graph with vertex set $P$. Examples of crossing-free structures include triangulations of $P$, spanning cycles of $P$, also known as polygonalizations…

Computational Geometry · Computer Science 2013-12-18 Victor Alvarez , Karl Bringmann , Radu Curticapean , Saurabh Ray

In multivariate spline regression, the number and locations of knots influence the performance and interpretability significantly. However, due to non-differentiability and varying dimensions, there is no desirable frequentist method to…

Methodology · Statistics 2024-05-24 Junhui He , Ying Yang , Jian Kang

Symmetries of knots have been studied extensively, and strongly invertible knots are one of them. Lamm defined the equivariant crossing number $c_t(K)$, the minimum crossing number among all symmetric diagrams for a strongly invertible knot…

Geometric Topology · Mathematics 2023-04-04 Jundai Nanasawa

We will strengthen the known upper and lower bounds on the delta-crossing number of knots in therms of the triple-crossing number. The latter bound turns out to be strong enough to obtain (unknown values of) triple-crossing numbers for a…

Geometric Topology · Mathematics 2023-03-06 Michal Jablonowski

This is a report on our ongoing research on a combinatorial approach to knot recognition, using coloring of knots by certain algebraic objects called quandles. The aim of the paper is to summarize the mathematical theory of knot coloring in…

Geometric Topology · Mathematics 2016-03-03 Andrew Fish , Alexei Lisitsa , David Stanovský

We apply Bayesian optimization and reinforcement learning to a problem in topology: the question of when a knot bounds a ribbon disk. This question is relevant in an approach to disproving the four-dimensional smooth Poincar\'e conjecture;…

Geometric Topology · Mathematics 2025-06-16 Sergei Gukov , James Halverson , Ciprian Manolescu , Fabian Ruehle

We present a practical algorithm to test whether a 3-manifold given by a triangulation or an ideal triangulation contains a closed essential surface. This property has important theoretical and algorithmic consequences. As a testament to…

Geometric Topology · Mathematics 2025-07-01 Benjamin A. Burton , Stephan Tillmann

The non-orientable 4-genus of a knot in the 3-sphere is defined as the smallest first Betti number of any non-orientable surface smoothly and properly embedded in the 4-ball, with boundary the given knot. We compute the non-orientable…

Geometric Topology · Mathematics 2020-09-09 Stanislav Jabuka , Tynan Kelly

We use the rational Witt class of a knot in the 3-sphere as a tool for addressing questions about its unknotting number. We apply these tools to several low crossing knots (151 knots with 11 crossing and 100 knots with 12 crossings) and to…

Geometric Topology · Mathematics 2009-07-15 Stanislav Jabuka

The list of knots with up to 10 crossings is commonly referred to as the Rolfsen Table. This paper presents a way to generate the Rolfsen table in a simple, clear, and reproducible manner. The methods we use are similar to those used by J.…

Geometric Topology · Mathematics 2017-05-31 Andrey Boris Khesin