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The Alexander biquandle of a virtual knot or link is a module over a 2-variable Laurent polynomial ring which is an invariant of virtual knots and links. The elementary ideals of this module are then invariants of virtual isotopy which…

Geometric Topology · Mathematics 2013-09-30 Alissa S. Crans , Allison Henrich , Sam Nelson

We extend the quandle cocycle invariant to oriented singular knots and links using algebraic structures called \emph{oriented singquandles} and assigning weight functions at both regular and singular crossings. This invariant coincides with…

Geometric Topology · Mathematics 2021-03-02 Jose Ceniceros , Indu R. Churchill , Mohamed Elhamdadi , Mustafa Hajij

In this paper we introduce a new invariant of virtual knots and links that is non-trivial for infinitely many virtuals, but is trivial on classical knots and links. The invariant is initially be expressed in terms of a relative of the…

Geometric Topology · Mathematics 2007-05-23 Louis H. Kauffman

In this paper, we define the parity virtual Alexander polynomial following the work of BDGGHN [1] and Kaestner and Kauffman [10]. The properties of this invariant are explored and some examples are computed. In particular, the invariant…

Geometric Topology · Mathematics 2019-07-23 Heather A. Dye , Aaron Kaestner

Defined by Joyce and Matveev, the fundamental quandle is a complete invariant of oriented classical knots. We consider invariants of knots defined from quotients of the fundamental quandle. In particular, we introduce the fundamental Latin…

Geometric Topology · Mathematics 2014-04-25 Sam Nelson , Sherilyn Tamagawa

Multi-virtual knot theory was introduced in $2024$ by the first author. In this paper, we initiate the study of algebraic invariants of multi-virtual links. After determining a generating set of (oriented) multi-virtual Reidemeister moves,…

Geometric Topology · Mathematics 2025-04-15 Louis H. Kauffman , Sujoy Mukherjee , Petr Vojtěchovský

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

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

In the present paper, we describe new approaches for constructing virtual knot invariants. The main background of this paper comes from formulating and bringing together the ideas of biquandle (Kauffman and Radford) the virtual quandle…

Geometric Topology · Mathematics 2007-05-23 Louis Kauffman , Vassily Olegovich Manturov

We investigate connections between biquandle colorings, quiver enhancements, and several notions of the bridge numbers $b_i(K)$ for virtual links, where $i=1,2$. We show that for any positive integers $m \leq n$, there exists a virtual link…

Geometric Topology · Mathematics 2025-04-15 Tirasan Khandhawit , Puttipong Pongtanapaisan , Brandon Wang

We enhance the psyquandle counting invariant for singular knots and pseudoknots using quivers analogously to quandle coloring quivers. This enables us to extend the in-degree polynomial invariants from quandle coloring quiver theory to the…

Geometric Topology · Mathematics 2021-07-14 Jose Ceniceros , Anthony Christiana , Sam Nelson

We describe a way of representing finite biquandles with n elements as 2n x 2n block matrices. Any finite biquandle defines an invariant of virtual knots through counting homomorphisms. The counting invariants of non-quandle biquandles can…

Geometric Topology · Mathematics 2007-05-23 Sam Nelson , John Vo

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

Flat virtual links are some variant of links, and semiquandles are counterparts of quandles or biquandles, which axiomize the Reidemeister-like moves. In this paper, we give some example of semiquandle and introduce an invariant for flat…

Geometric Topology · Mathematics 2024-11-08 Nozomu Sekino

We define a generalization of virtual links to arbitrary dimensions by extending the geometric definition due to Carter et al. We show that many homotopy type invariants for classical links extend to invariants of virtual links. We also…

Geometric Topology · Mathematics 2014-07-03 Blake Winter

In this short survey article we collect the current state of the art in the nascent field of \textit{quantum enhancements}, a type of knot invariant defined by collecting values of quantum invariants of knots with colorings by various…

Geometric Topology · Mathematics 2026-02-19 Sam Nelson

We define invariants of unoriented knots and links by enhancing the integral kei counting invariant Phi_X^Z (K) for a finite kei X using representations of the kei algebra, Z_K[X], a quotient of the quandle algebra Z[X] defined by…

Geometric Topology · Mathematics 2011-02-23 Mike Grier , Sam Nelson

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

We introduce birack brackets, skein invariants of birack-colored framed classical and virtual knots and links with values in a commutative unital ring. The multiset of birack bracket values over the homset from a framed link's fundamental…

Geometric Topology · Mathematics 2026-02-09 Sam Nelson , Haoqi Tom Tang

In this paper we study the chord index of virtual knots, which can be thought of as an extension of the chord parity. We show how to use the chord index to define finite type invariants of virtual knots. The notions of indexed Jones…

Geometric Topology · Mathematics 2026-05-26 Zhiyun Cheng