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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

In this paper, we introduce invariants of virtual knotoids based on biquandles and biquandle virtual brackets. We show that one of these invariants, namely biquandle virtual bracket matrix, is a proper enhancement of the other invariants…

Algebraic Topology · Mathematics 2025-07-11 Neslihan Gügümcü , Hamdi Kayaslan

We define a family of quiver representation-valued invariants of oriented classical and virtual knots and links associated to a choice of finite quandle $X$, abelian group $A$, set of quandle 2-cocycles $C\subset H^2_Q(x;A)$, choice of…

Geometric Topology · Mathematics 2024-12-24 Sam Nelson

In the paper we introduce a general approach how for a given virtual biquandle multi-switch $(S,V)$ on an algebraic system $X$ (from some category) and a given virtual link $L$ construct an algebraic system $X_{S,V}(L)$ (from the same…

Algebraic Topology · Mathematics 2020-01-22 Valeriy Bardakov , Timur Nasybullov

Introduced in arXiv:2211.12606, biquandle arrow weight invariants are enhancements of the biquandle counting invariant for oriented virtual and classical knots defined from biquandle-colored Gauss diagrams using a tensor over an abelian…

Geometric Topology · Mathematics 2025-01-30 Sam Nelson , Migiwa Sakurai

A group invariant for links in thickened closed orientable surfaces is studied. Associated polynomial invariants are defined. The group detects nontriviality of a virtual link and determines its virtual genus.

Geometric Topology · Mathematics 2014-10-01 J. Scott Carter , Daniel S. Silver , Susan G. Williams

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

Given a biquandle $(X, S)$, a function $\tau$ with certain compatibility and a pair of {\em non commutative cocyles} $f,h:X \times X\to G$ with values in a non necessarily commutative group $G$, we give an invariant for singular knots /…

Geometric Topology · Mathematics 2019-10-10 Marco Farinati , Juliana García Galofre

The forbidden moves in virtual knot theory can be used to unknot any knot, virtual or classical; however, multi-component crossings in links can still survive, resulting a fused link. Using the forbidden moves, we categorify fused links…

Geometric Topology · Mathematics 2026-05-22 Sam Nelson , Stella Shah

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

A knot invariant is called skein if it is determined by a finite number of skein relations. In the paper we discuss some basic properties of skein invariants and mention some known examples of skein invariants.

Geometric Topology · Mathematics 2024-12-30 Igor Nikonov

We define an invariant of tangles and framed tangles given a finite crossed module and a pair of functions, called a Reidemeister pair, satisfying natural properties. We give several examples of Reidemeister pairs derived from racks,…

Geometric Topology · Mathematics 2017-05-23 Joao Faria Martins , Roger Picken

In this paper, we introduce biquandle power brackets, an infinite family of invariants of oriented links containing the classical skein invariants and the quandle and biquandle 2-cocycle invariants as special cases. Biquandle power brackets…

Geometric Topology · Mathematics 2024-01-23 Neslihan Gügümcü , Sam Nelson

We define numerical link-homotopy invariants of link maps of any number of components, which naturally generalize the Kirk invariant. The Kirk invariant is a link-homotopy invariant of 2-component link maps given by linking numbers of loops…

Geometric Topology · Mathematics 2023-11-22 Benjamin Audoux , Jean-Baptiste Meilhan , Akira Yasuhara

We introduce the notion of N-reduced dynamical cocycles and use these objects to define enhancements of the rack counting invariant for classical and virtual knots and links. We provide examples to show that the new invariants are not…

Geometric Topology · Mathematics 2011-08-23 Alissa S. Crans , Sam Nelson , Aparna Sarkar

We extend the quandle cocycle invariant to the context of stuck links. More precisely, we define an invariant of stuck links by assigning Boltzmann weights at both classical and stuck crossings. As an application, we define a…

Geometric Topology · Mathematics 2023-03-29 Jose Ceniceros , Mohamed Elhamdadi , Brendan Magill , Gabriana Rosario

This paper describes a polynomial invariant of virtual knots that is defined in terms of an integer labeling of the virtual knot diagram. This labeling is seen to derive from an essentially unique structure of affine flat biquandle for flat…

Algebraic Topology · Mathematics 2014-07-25 Louis H. Kauffman

Every classical or virtual knot is equivalent to the unknot via a sequence of extended Reidemeister moves and the so-called forbidden moves. The minimum number of forbidden moves necessary to unknot a given knot is an invariant we call the…

Geometric Topology · Mathematics 2018-08-14 Alissa Crans , Sandy Ganzell , Blake Mellor

In this article, we introduce rack invariants of oriented Legendrian knots in the 3-dimensional Euclidean space endowed with the standard contact structure, which we call Legendrian racks. These invariants form a generalization of the…

Geometric Topology · Mathematics 2017-07-04 Dheeraj Kulkarni , T. V. H. Prathamesh

We define a knot/link invariant using set theoretical solutions $(X,\sigma)$ of the Yang-Baxter equation and non commutative 2-cocycles. We also define, for a given $(X,\sigma)$, a universal group Unc(X) governing all 2-cocycles in $X$, and…

Geometric Topology · Mathematics 2015-07-09 Marco A. Farinati , Juliana García Galofre