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Related papers: Enhancements of the rack counting invariant via N-…

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We introduce a modified rack algebra Z[X] for racks X with finite rack rank N. We use representations of Z[X] into rings, known as rack modules, to define enhancements of the rack counting invariant for classical and virtual knots and…

Geometric Topology · Mathematics 2010-08-04 Aaron Haas , Garret Heckel , Sam Nelson , Jonah Yuen , Qingcheng Zhang

Biracks are algebraic structures related to knots and links. We define a new enhancement of the birack counting invariant for oriented classical and virtual knots and links via algebraic structures called birack dynamical cocycles. The new…

Geometric Topology · Mathematics 2012-05-22 Sam Nelson , Emily Watterberg

We study Coxeter racks over $\mathbb{Z}_n$ and the knot and link invariants they define. We exploit the module structure of these racks to enhance the rack counting invariants and give examples showing that these enhanced invariants are…

Geometric Topology · Mathematics 2008-08-13 Sam Nelson , Ryan Wieghard

We study rack polynomials and the link invariants they define. We show that constant action racks are classified by their generalized rack polynomials and show that $ns^at^a$-quandles are not classified by their generalized quandle…

Geometric Topology · Mathematics 2019-03-13 Tim Carrell , Sam Nelson

The theory of quandle (co)homology and cocycle knot invariants is rapidly being developed. We begin with a summary of these recent advances. One such advance is the notion of a dynamical cocycle. We show how dynamical cocycles can be used…

Geometric Topology · Mathematics 2007-05-23 J. Scott Carter , Angela Harris , Marina Appiou Nikiforou , Masahico Saito

We define ambient isotopy invariants of oriented knots and links using the counting invariants of framed links defined by finite racks. These invariants reduce to the usual quandle counting invariant when the rack in question is a quandle.…

Geometric Topology · Mathematics 2013-07-30 Sam Nelson

We bring cocycle enhancement theory to the case of psyquandles. Analogously to our previous work on virtual biquandle cocycle enhancements, we define enhancements of the psyquandle counting invariant via pairs of a biquandle 2-cocycle and a…

Geometric Topology · Mathematics 2020-10-01 Jose Ceniceros , Sam Nelson

We enhance the quandle counting invariants of oriented classical and virtual knots and links using a construction similar to quandle modules but inspired by symplectic quandle operations rather than Alexander quandle operations. Given a…

Geometric Topology · Mathematics 2023-04-18 Will Gilroy , Sam Nelson

We introduce an associative algebra Z[X,S] associated to a birack shadow and define enhancements of the birack counting invariant for classical knots and links via representations of Z[X,S] known as shadow modules. We provide examples which…

Geometric Topology · Mathematics 2011-06-03 Sam Nelson , Katie Pelland

We extend the Yang-Baxter cocycle invariants for virtual knots by augmenting Yang-Baxter 2-cocycles with cocycles from a cohomology theory associated to a virtual biquandle structure. These invariants coincide with the classical Yang-Baxter…

Geometric Topology · Mathematics 2008-02-22 Jose Ceniceros , Sam Nelson

The aim of this paper is to define a homology theory for racks with finite rank N and use it to define invariants of knots generalizing the CJKLS 2-cocycle invariants related to the invariants defined in [15]. For this purpose, we prove…

Geometric Topology · Mathematics 2011-05-24 Mohamed Elhamdadi , Sam Nelson

This paper is a brief overview of some of our recent results in collaboration with other authors. The cocycle invariants of classical knots and knotted surfaces are summarized, and some applications are presented.

Geometric Topology · Mathematics 2007-05-23 J. Scott Carter , Masahico Saito

We introduce two new families of polynomial invariants of oriented classical and virtual knots and links defined as decategorfications of the quandle coloring quiver. We provide examples to illustrate the computation of the invariants, show…

Geometric Topology · Mathematics 2025-08-18 Anusha Kabra , Sam Nelson

We extend the rack algebra Z[X] defined by Andruskiewitsch and Grana to the case of biracks, enabling a notion of birack modules. We use these birack modules to define an enhancement of the birack counting invariant generalizing the birack…

Geometric Topology · Mathematics 2012-12-14 Regina Bauernschmidt , Sam Nelson

We introduce a new invariant of tangles along with an algebraic framework in which to understand it. We claim that the invariant contains the classical Alexander polynomial of knots and its multivariable extension to links. We argue that of…

Quantum Algebra · Mathematics 2013-09-16 Dror Bar-Natan , Sam Selmani

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

We describe a presentation for the augmented fundamental rack of a link in the lens space $L(p,1)$. Using this presentation, the (enhanced) counting rack invariants that have been defined for the classical links are applied to the links in…

Geometric Topology · Mathematics 2019-10-01 Eva Horvat

A polynomial invariant of virtual links, arising from an invariant of links in thickened surfaces introduced by Jaeger, Kauffman, and Saleur, is defined and its properties are investigated. Examples are given that the invariant can detect…

Geometric Topology · Mathematics 2007-05-23 J. Sawollek

We introduce a new class of quantum enhancements we call biquandle brackets, which are customized skein invariants for biquandle colored links.Quantum enhancements of biquandle counting invariants form a class of knot and link invariants…

Geometric Topology · Mathematics 2017-02-17 Sam Nelson , Michael E. Orrison , Veronica Rivera

We use the structure of skew braces to enhance the biquandle counting invariant for virtual knots and links for finite biquandles defined from skew braces. We introduce two new invariants: a single-variable polynomial using skew brace…

Geometric Topology · Mathematics 2022-06-30 Melody Chang , Sam Nelson
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