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In this paper we present a sequence of link invariants, defined from twisted Alexander polynomials, and discuss their effectiveness in distinguish knots. In particular, we recast and extend by geometric means a recent result of Silver and…

Geometric Topology · Mathematics 2018-12-24 Stefan Friedl , Stefano Vidussi

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 use crossing parity to construct a generalization of biquandles for virtual knots which we call Parity Biquandles. These structures include all biquandles as a standard example referred to as the even parity biquandle. Additionally, we…

Geometric Topology · Mathematics 2011-03-16 Aaron Kaestner , Louis H. Kauffman

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 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

Virtual knot theory is a generalization (discovered by the author in 1996) of knot theory to the study of all oriented Gauss codes. (Classical knot theory is a study of planar Gauss codes.) Graph theory studies non-planar graphs via…

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

In the paper of Yu. A. Mikhalchishina for an arbitrary virtual link $L$ three groups $G_{1,r}(L)$, $r>0$, $G_{2}(L)$ and $G_{3}(L)$ were defined. In the present paper these groups for the virtual trefoil are investigated. The structure of…

Geometric Topology · Mathematics 2018-04-18 V. G. Bardakov , Yu. A. Mikhalchishina , M. V. Neshchadim

Piecewise-linear virtual knots are discussed and classified up to edge index six.

Geometric Topology · Mathematics 2009-07-14 Neil R. Nicholson

The weak splitting number $wsp(L)$ of a link $L$ is the minimal number of crossing changes needed to turn $L$ into a split union of knots. We describe conditions under which certain $\mathbb{R}$-valued link invariants give lower bounds on…

Geometric Topology · Mathematics 2020-05-12 Alberto Cavallo , Carlo Collari , Anthony Conway

We define new notions of groups of virtual and welded knots (or links) and we study their relations with other invariants, in particular the Kauffman group of a virtual knot.

Geometric Topology · Mathematics 2012-04-17 Valeriy G. Bardakov , Paolo Bellingeri

In this paper, we introduce the concept of the warping degree for twisted knots, construct an invariant for them, and utilize it to establish a labeling scheme for these knots, known as ``warping labeling". We have identified that a warping…

Geometric Topology · Mathematics 2024-06-14 Komal Negi , Ayaka Shimizu , Madeti Prabhakar

In this paper, a regional knot invariant is constructed. Like the Wirtinger presentation of a knot group, each planar region contributes a generator, and each crossing contributes a relation. The invariant is call a tridle of the link. As…

Geometric Topology · Mathematics 2017-03-20 Zhiqing Yang

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

A detailed version of preprint "Self-linking number of a real algebraic link" by the same author, alg-geom/9410030. For a nonsingular real algebraic curve in 3-dimensional projective space or 3-sphere, a new integer-valued characteristic is…

Algebraic Geometry · Mathematics 2007-05-23 Oleg Viro

Kuperberg [Algebr. Geom. Topol. 3 (2003) 587-591] has shown that a virtual knot corresponds (up to generalized Reidemeister moves) to a unique embedding in a thichened surface of minimal genus. If a virtual knot diagram is equivalent to a…

Geometric Topology · Mathematics 2014-10-01 H. A. Dye , Louis H. Kauffman

We discuss Vassiliev invariants for virtual knots, expanding upon the theory of quantum virtual knot invariants developed in arXiv:1509.00578. In particular, following the theory of quantum invariants we work with 'rotational' virtual…

Geometric Topology · Mathematics 2022-09-20 Wout Moltmaker , Louis H. Kauffman

For a virtual knot $K$ and an integer $r$ with $r\geq2$, we introduce a method of constructing an $r$-component virtual link $L(K;r)$, which we call the $r$-multiplexing of $K$. Every invariant of $L(K;r)$ is an invariant of $K$. We give a…

Geometric Topology · Mathematics 2023-12-04 Kodai Wada

We generalize the index polynomial invariant to the case of virtual tangles. Three polynomial invariants result from this generalization; we give a brief overview of their definition and some basic properties.

Geometric Topology · Mathematics 2019-04-23 Nicolas Petit

We consider the question of which virtual knots have finite fundamental medial bikei. We describe and implement an algorithm for completing a presentation matrix of a medial bikei to an operation table, determining both the cardinality and…

Geometric Topology · Mathematics 2017-04-05 Julien Chien , Sam Nelson

Given a virtual knot $K$, we construct a group $VG_K$ called the virtual knot group, and we use the elementary ideals of $VG_K$ to define invariants of $K$ called the virtual Alexander invariants. For instance, associated to the $k=0$ ideal…

Geometric Topology · Mathematics 2015-05-07 Hans U. Boden , Emily Dies , Anne Isabel Gaudreau , Adam Gerlings , Eric Harper , Andrew J. Nicas