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We introduce \textit{Kaestner brackets}, a generalization of biquandle brackets to the case of parity biquandles. This infinite set of quantum enhancements of the biquandle counting invariant for oriented virtual knots and links includes…

Geometric Topology · Mathematics 2020-06-12 Forest Kobayashi , Sam Nelson

Three new knot invariants are defined using cocycles of the generalized quandle homology theory that was proposed by Andruskiewitsch and Gra\~na. We specialize that theory to the case when there is a group action on the coefficients. First,…

Geometric Topology · Mathematics 2007-05-23 J. Scott Carter , Mohamed Elhamdadi , Matias Graña , Masahico Saito

We introduce new skein invariants of links based on a procedure where we first apply the skein relation only to crossings of distinct components, so as to produce collections of unlinked knots. We then evaluate the resulting knots using a…

Geometric Topology · Mathematics 2019-04-04 Louis H. Kauffman , Sofia Lambropoulou

Quandle 2-cocycles define invariants of classical and virtual knots, and extensions of quandles. We show that the quandle 2-cocycle invariant with respect to a non-trivial $2$-cocycle is constant, or takes some other restricted form, for…

Geometric Topology · Mathematics 2016-03-22 W. Edwin Clark , Masahico Saito

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

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 introduce augmented biracks and define a (co)homology theory associated to augmented biracks. The new homology theory extends the previously studied Yang-Baxter homology with a combinatorial formulation for the boundary map and…

Geometric Topology · Mathematics 2013-09-09 Jose Ceniceros , Mohamed Elhamdadi , Matthew Green , Sam Nelson

In this survey we summarize results regarding the Kauffman bracket, HOMFLYPT, Kauffman 2-variable and Dubrovnik skein modules, and the Alexander polynomial of links in lens spaces, which we represent as mixed link diagrams. These invariants…

Geometric Topology · Mathematics 2018-08-17 Boštjan Gabrovšek , Eva Horvat

The mock Alexander polynomial is an extension of the classical Alexander polynomial, defined and studied for (virtual) knots and knotoids by the second and third authors. In this paper we consider the mock Alexander polynomial for…

Geometric Topology · Mathematics 2024-06-13 Joanna A. Ellis-Monaghan , Neslihan Gügümcü , Louis H. Kauffman , Wout Moltmaker

We define enhancements of the quandle counting invariant for knots and links with a finite labeling quandle Q embedded in the quandle of units of a Lie algebra \mathfrak{a} using Lie ideals. We provide examples demonstrating that the…

Geometric Topology · Mathematics 2015-07-29 Gillian Roxanne Grindstaff , Sam Nelson

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

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

We introduce an infinite family of quantum enhancements of the biquandle counting invariant we call biquandle virtual brackets. Defined in terms of skein invariants of biquandle colored oriented knot and link diagrams with values in a…

Geometric Topology · Mathematics 2019-08-28 Sam Nelson , Kanako Oshiro , Ayaka Shimizu , Yoshiro Yaguchi

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 consider involutory virtual biracks with good involutions, also known as symmetric involutory virtual biracks. Any good involution on an involutory virtual birack defines an enhancement of the counting invariant. We provide examples…

Geometric Topology · Mathematics 2017-09-12 Melinda Ho , Sam Nelson

The homology and cohomology of quandles and racks are used in knot theory: given a finite quandle and a cocycle, we can construct a knot invariant. This is a quick introductory survey to the invariants of knots derived from quandles and…

Geometric Topology · Mathematics 2007-05-23 Seiichi Kamada

Biquandle brackets define invariants of classical and virtual knots and links using skein invariants of biquandle-colored knots and links. Biquandle coloring quivers categorify the biquandle counting invariant in the sense of defining…

Geometric Topology · Mathematics 2021-09-14 Pia Cosma Falkenburg , Sam Nelson

A rack shadow is a set X with a rack action by a rack R, analogous to a vector space over a field. We use shadow colorings of classical link diagrams to define enhanced rack counting invariants and show that the enhanced invariants are…

Geometric Topology · Mathematics 2010-07-14 Wesley Chang , Sam Nelson

Geometric interpretations of some virtual knot invariants are given in terms of invariants of links in $\mathbb{S}^3$. Alexander polynomials of almost classical knots are shown to be specializations of the multi-variable Alexander…

Geometric Topology · Mathematics 2018-07-27 Micah Chrisman , Robert G. Todd

We use planar 4-valent graphs and a graphical calculus involving such graphs to construct an invariant for balanced-oriented, knotted 4-valent graphs. Our invariant is an extension of the $sl(n)$ polynomial for classical knots and links. We…

Geometric Topology · Mathematics 2026-02-03 Carmen Caprau , Victoria Wiest