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We introduce topological invariants of knots and braid conjugacy classes, in the form of differential graded algebras, and present an explicit combinatorial formulation for these invariants. The algebras conjecturally give the relative…

Geometric Topology · Mathematics 2014-11-11 Lenhard Ng

We extend previous work by using a combination of band surgeries and known bounds to compute $\gamma_4(T_{4n, (2n\pm1)^2 + 4n-2}) = 2n-1$ for all $n \geq 1$. We further generalize this result by showing that $\gamma_4(T_{4n + 2k, n(4n + 2k)…

Geometric Topology · Mathematics 2025-07-31 Shreya Sinha

An invariant $\mu_{\alpha}(K)$ of fibred knots $K$ in a homology sphere is defined for each $\alpha \in {\bold S}{\bold U}_n$ as follows. Since the knot is fibred, the knot complement is described by an element of the mapping class group,…

q-alg · Mathematics 2016-09-08 H. U. Boden

A connect sum formula for the two variable series invariant of a complement of knot is proposed. We provide two kinds of numerical evidence for the proposed formula by examining various torus knots.

Geometric Topology · Mathematics 2021-09-30 John Chae

Given a diagram D of a knot K, we give easily computable bounds for Rasmussen's concordance invariant s(K). The bounds are not independent of the diagram D chosen, but we show that for diagrams satisfying a given condition the bounds are…

Geometric Topology · Mathematics 2012-12-12 Andrew Lobb

In this paper, we study the behavior of $\Upsilon_K(t)$ under the cabling operation, where $\Upsilon_K(t)$ is the knot concordance invariant defined by Ozsv\'ath, Stipsicz, and Szab\'o, associated to a knot $K\subset S^3$. The main result…

Geometric Topology · Mathematics 2021-08-18 Wenzhao Chen

The stable 4-genus of a knot K in 3-space is the limiting value of g_4(nK)/n, where g_4 denotes the 4-genus and n goes to infinity. This induces a seminorm on CQ, the concordance group tensored with the rational numbers. Basic properties of…

Geometric Topology · Mathematics 2015-03-13 Charles Livingston

The 2-loop polynomial is a polynomial presenting the 2-loop part of the Kontsevich invariant of knots. We show a cabling formula for the 2-loop polynomial of knots. In particular, we calculate the 2-loop polynomial for torus knots.

Geometric Topology · Mathematics 2007-05-23 Tomotada Ohtsuki

We determine the relationship between the contact structure induced by a fibered knot, K, in the three-sphere and the contact structures induced by its various cables. Understanding this relationship allows us to classify fibered cable…

Geometric Topology · Mathematics 2008-04-29 Matthew Hedden

The fusion number of a ribbon knot is the minimal number of 1-handles needed to construct a ribbon disk. The strong homotopy fusion number of a ribbon knot is the minimal number of 2-handles in a handle decomposition of a ribbon disk…

Geometric Topology · Mathematics 2020-03-27 Jennifer Hom , Sungkyung Kang , JungHwan Park

Knot contact homology is an invariant of knots derived from Legendrian contact homology which has numerous connections to the knot group. We use basic properties of knot groups to prove that knot contact homology detects every torus knot.…

Geometric Topology · Mathematics 2015-09-08 Cameron Gordon , Tye Lidman

We introduce a 4-dimensional analogue of the rational Seifert genus of a knot $K\subset Y$, which we call the rational slice genus, that measures the complexity of a homology class in $H_2(Y\times [0,1],K;\mathbb{Q})$. Our main theorem is a…

Geometric Topology · Mathematics 2023-09-01 Katherine Raoux , Matthew Hedden

I present a formula for the Casson invariant of knots associated with divides. The formula is written in terms of Arnold's invariants of pieces of the divide. Various corollaries are discussed.

Geometric Topology · Mathematics 2007-05-23 Alexander Shumakovitch

We use the Blanchfield form to obtain a lower bound on the equivariant slice genus of a strongly invertible knot. For our main application, let $K$ be a genus one strongly invertible slice knot with nontrivial Alexander polynomial. We show…

Geometric Topology · Mathematics 2022-08-25 Allison N. Miller , Mark Powell

We present a lower bound on the stable $4$-genus of a knot based on Casson-Gordon $\tau$-signatures. We compute the lower bound for an infinite family of knots, the twist knots, and show that a twist knot is torsion in the knot concordance…

Geometric Topology · Mathematics 2023-02-27 Damian Iltgen

New invariants for 2-dimensional cell complexes are defined, which can be interpreted as curvature bounds. These invariants are proved to be rational and computable in a companion article. This document is a survey that collects theorems…

Group Theory · Mathematics 2024-05-16 Henry Wilton

We give a formula of the Upsilon invariant of any L-space cable knot $K_{p,q}$ using $p,\Upsilon_K$ and $\Upsilon_{T_{p,q}}$. The integral value of the Upsilon invariant gives a ${\mathbb Q}$-valued knot concordance invariant. We compute…

Geometric Topology · Mathematics 2021-10-01 Motoo Tange

We use four dimensional techniques to derive general bounds on the $\tau$ invariant of a satellite knot in $S^{3}$.

Geometric Topology · Mathematics 2016-01-20 Lawrence P. Roberts

We present a topological interpretation of knot and braid contact homology in degree zero, in terms of cords and skein relations. This interpretation allows us to extend the knot invariant to embedded graphs and higher-dimensional knots. We…

Geometric Topology · Mathematics 2014-11-11 Lenhard Ng

We prove that every nontrivial cable of the figure-eight knot has infinite order in the smooth knot concordance group. Our main contribution is a uniform proof that applies to all $(2n,1)$-cables of the figure-eight knot. To this end, we…

Geometric Topology · Mathematics 2025-05-07 Sungkyung Kang , JungHwan Park , Masaki Taniguchi