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200 papers

This paper studies knots in three dimensional projective space. Our technique is to associate a virtual link to a link in projective space so that equivalent projective links go to equivalent virtual links (modulo a special flype move). We…

Geometric Topology · Mathematics 2025-11-11 Louis H. Kauffman , Rama Mishra , Visakh Narayanan

We introduce quiver representation-valued invariants of oriented virtual knots and links associated to a choice of finite virtual biquandle, abelian group, set of virtual Boltzmann weights, commutative unital ring and set of virtual…

Geometric Topology · Mathematics 2025-11-18 Alexander Bishop , Jose Ceniceros , Sam Nelson

Multivariable Alexander invariants of algebraic links calculated in terms of algebro-geometric invariants (polytopes and ideals of quasiadjunction). The relations with log-canonical divisors, the multiplier ideals and a semicontinuity…

Algebraic Geometry · Mathematics 2007-05-23 A. Libgober

F-polynomials for virtual knots were defined by Kaur, Prabhakar and Vesnin in 2018 using flat virtual knot invariants. These polynomials naturally generalize Kauffman's affine index polynomial and use smoothing in classical crossing of a…

Geometric Topology · Mathematics 2021-11-09 Amrendra Gill , Maxim Ivanov , Madeti Prabhakar , Andrei Vesnin

We define counting and cocycle enhancement invariants of virtual knots using parity biquandles. These invariants are determined by pairs consisting of a biquandle 2-cocycle \phi^0 and a map \phi^1 with certain compatibility conditions…

Geometric Topology · Mathematics 2016-06-16 Aaron Kaestner , Sam Nelson , Leo Selker

The connected sum of two flat virtual knots depends on the choice of diagrams and basepoints. We show that any minimal crossing diagram of a composite flat virtual knot is a connected sum diagram. We also show the crossing number of flat…

Geometric Topology · Mathematics 2024-07-26 Jie Chen

We show that a variation of Milnor's $\bar\mu$-invariants, the so-called Campbell-Hausdorff invariants introduced recently by Stefan Papadima, are of finite type with respect to {\it marked singular links}. These link invariants are…

q-alg · Mathematics 2008-02-03 Xiao-Song Lin

We consider the group of pure welded braids (also known as loop braids) up to (link-)homotopy. The pure welded braid group classically identifies, via the Artin action, with the group of basis-conjugating automorphisms of the free group,…

Algebraic Topology · Mathematics 2024-07-10 Jacques Darné

It is known that the writhe calculated from any reduced alternating link diagram of the same (alternating) link has the same value. That is, it is a link invariant if we restrict ourselves to reduced alternating link diagrams. This is due…

Geometric Topology · Mathematics 2020-09-29 Yuanan Diao , Van Pham

Given any unoriented link diagram, a group of new knot invariants are constructed. Each of them satisfies a generalized 4 term skein relation. The coefficients of each invariant is from a commutative ring. Homomorphisms and representations…

Geometric Topology · Mathematics 2010-04-14 Zhiqing Yang , Jifu Xiao

We generalize Milnor link invariants to all types of surface-links in $4$--space (possibly with boundary). This is achieved by using the notion of cut-diagram, which is a 2-dimensional generalization of Gauss diagrams, associated to…

Geometric Topology · Mathematics 2025-12-02 Benjamin Audoux , Jean-Baptiste Meilhan , Akira Yasuhara

Given a suitable link map f into a manifold M, we constructed, in [10], link homotopy invariants kappa(f) and mu(f). In the present paper we study the case M=S^n x R^{m - n} in detail. Here mu(f) turns out to be the starting term of a whole…

Algebraic Topology · Mathematics 2007-05-23 Ulrich Koschorke

We use Polyak's skein relation to give a new proof that Milnor's string link homotopy invariants are finite type invariants, and to develop a recursive relation for their associated weight systems. We show that the obstruction to the…

Geometric Topology · Mathematics 2008-03-07 Blake Mellor

Fixing two concordant links in $3$--space, we study the set of all embedded concordances between them, as knotted annuli in $4$--space. When regarded up to surface-concordance or link-homotopy, the set $\mathcal{C}(L)$ of concordances from…

Geometric Topology · Mathematics 2021-05-06 Jean-Baptiste Meilhan , Akira Yasuhara

We describe a method of encoding various types of link diagrams, including those with classical, flat, rigid, welded, and virtual crossings. We show that this method may be used to encode link diagrams, up to equivalence, in a notation…

Geometric Topology · Mathematics 2013-05-03 Chad Musick

J.-B. Meilhan and the second author showed that any Milnor $\bar{\mu}$-invariant of length between 3 and $2k+1$ can be represented as a combination of HOMFLYPT polynomial of knots obtained by certain band sum of the link components, if all…

Geometric Topology · Mathematics 2013-04-09 Yuka Kotorii , Akira Yasuhara

The writhe polynomial is a fundamental invariant of an oriented virtual knot. We introduce a kind of local moves for oriented virtual knots called shell moves. The first aim of this paper is to prove that two oriented virtual knots have the…

Geometric Topology · Mathematics 2019-05-10 Takuji Nakamura , Yasutaka Nakanishi , Shin Satoh

We study virtualized Delta, sharp, and pass moves for oriented virtual links, and give necessary and sufficient conditions for two oriented virtual links to be related by the local moves. In particular, they are unknotting operations for…

Geometric Topology · Mathematics 2024-01-25 Takuji Nakamura , Yasutaka Nakanishi , Shin Satoh , Kodai Wada

We survey some tools and techniques for determining geometric properties of a link complement from a link diagram. In particular, we survey the tools used to estimate geometric invariants in terms of basic diagrammatic link invariants. We…

Geometric Topology · Mathematics 2019-09-27 David Futer , Efstratia Kalfagianni , Jessica S. Purcell

We first prove that, infinitely many pairs of trivial knot diagrams that are transformed into each other by applying Reidemeister moves I and III are NOT transformed into each other by a sequence of the Reidemeister moves I that increase…

Geometric Topology · Mathematics 2023-09-12 Kishin Sasaki