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We consider a quiver structure on the set of quandle colorings of an oriented knot or link diagram. This structure contains a wealth of knot and link invariants and provides a categorification of the quandle counting invariant in the most…

Geometric Topology · Mathematics 2018-10-09 Karina Cho , Sam Nelson

The number of colorings of a knot diagram by a quandle has been shown to be a knot invariant by CJKLS using quandle cohomology methods. In a previous paper by the second named author, the CJKLS invariant was refined and, in particular, it…

Geometric Topology · Mathematics 2007-05-23 F. Miguel Dionisio , Pedro Lopes

We introduce a new family of invariants of oriented classical and virtual knots and links using fares, maps from paths in biquandle-colored diagrams to an abelian coefficient group. We consider the cases of 1-fares and 2-fares, provide…

Geometric Topology · Mathematics 2026-02-09 Sam Nelson , Stella Shah

The knot coloring polynomial defined by Eisermann for a finite pointed group is generalized to an infinite pointed group as the longitudinal mapping invariant of a knot. In turn this can be thought of as a generalization of the quandle…

Geometric Topology · Mathematics 2018-02-27 W. Edwin Clark , Masahico Saito

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

Biquandle brackets are a type of quantum enhancement of the biquandle counting invariant for oriented knots and links, defined by a set of skein relations with coefficients which are functions of biquandle colors at a crossing. In this…

Geometric Topology · Mathematics 2019-09-04 Neslihan Gügümcü , Sam Nelson , Natsumi Oyamaguchi

In this paper we define and give examples of a family of polynomial invariants of virtual knots and links. They arise by considering certain 2$\times$2 matrices with entries in a possibly non-commutative ring, for example the quaternions.…

Geometric Topology · Mathematics 2007-05-23 Andrew Bartholomew , Roger Fenn

We introduce two kinds of structures, called v-structures and t-structures, on biquandles. These structures are used for colorings of diagrams of virtual links and twisted links such that the numbers of colorings are invariants. Given a…

Geometric Topology · Mathematics 2015-12-29 Naoko Kamada , Seiichi Kamada

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

A group-theoretical method, via Wada's representations, is presented to distinguish Kishino's virtual knot from the unknot. Biquandles are constructed for any group using Wada's braid group representations. Cocycle invariants for these…

Geometric Topology · Mathematics 2007-05-23 J. Scott Carter , Mohamed Elhamdadi , Masahico Saito , Daniel S. Silver , Susan G. Williams

Virtual knot theory is a generalization of knot theory which is based on Gauss chord diagrams and link diagrams on closed oriented surfaces. A twisted knot is a generalization of a virtual knot, which corresponds to a link diagram on a…

Geometric Topology · Mathematics 2015-12-04 Naoko Kamada

Quandle coloring quivers are directed graph-valued invariants of oriented knots and links, defined using a choice of finite quandle $X$ and set $S\subset\mathrm{Hom}(X,X)$ of endomorphisms. From a quandle coloring quiver, a polynomial knot…

Geometric Topology · Mathematics 2020-10-02 Jieon Kim , Sam Nelson , Minju Seo

In this paper we give the results of a computer search for biracks of small size and we give various interpretations of these findings. The list includes biquandles, racks and quandles together with new invariants of welded knots and…

Geometric Topology · Mathematics 2010-01-29 Andrew Bartholomew , Roger Fenn

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

Quandle Coloring Quivers are directed graph-valued invariants of classical and virtual knots and links associated to finite quandles. Quandle action quivers are subquivers of the full quandle coloring quiver associated to quandle actions by…

Geometric Topology · Mathematics 2024-04-02 Mason Cai , Sam Nelson

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

We introduce an infinite family of quiver representation-valued invariants of classical, virtual and surface-knots and links associated to a choice of finite biquandle, commutative unital ring, biquandle module and set of biquandle…

Geometric Topology · Mathematics 2025-11-04 Yewon Joung , Sam Nelson

We define an invariant of welded virtual knots from each finite crossed module by considering crossed module invariants of ribbon knotted surfaces which are naturally associated with them. We elucidate that the invariants obtained are non…

Geometric Topology · Mathematics 2017-05-23 Louis H. Kauffman , João Faria Martins

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

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