The virtual unknotting number of a virtual knot is the minimal number of crossing changes that makes the virtual knot to be the unknot, which is defined only for virtual knots virtually homotopic to the unknot. We focus on the virtual knot obtained from the standard (p,q)-torus knot diagram by replacing all crossings o…
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48 results for “virtual unknotting”
Paper introduces unknotting index for virtual knots.
problem Computing and understanding virtual knots.
method Using writhe invariants and relationships with virtual knot module.
result Existence of virtual knots with specific unknotting indices.
The paper finds virtual knots with specific unknotting indices.
problem Finding virtual knots with unknotting indices (n,m).
method Providing infinite families of virtual knots and links with specified unknotting indices.
result Existence of infinitely many distinct virtual knot diagrams with unknotting index (n,m).
The H(n)-move simplifies virtual and welded knots and links.
problem Tackling the unknotting of virtual and welded links.
method Extending the H(n)-move to virtual and welded links and showing their equivalence to Reidemeister moves.
result Virtualization and forbidden move can be realized by a finite sequence of generalized Reidemeister moves and H(n)-moves.
A new index measures how many changes are needed to turn virtual links into simple ones.
problem Determining the minimum number of changes needed to simplify virtual link diagrams.
method Defined the unknotting index using virtual crossings and classical changes, provided lower and upper bounds.
result Found bounds for the unknotting index of virtual links, including those from pretzel links.
Study virtualized Delta, Sharp, and Pass moves for oriented virtual knots and links.
problem Conditions for unknotting oriented virtual knots and links.
method Local moves (Delta, Sharp, Pass) for oriented virtual links.
result Lower bounds for the unknotting numbers are proven and shown to be best possible.
New virtualized Δ-move simplifies virtual knots and links.
problem Simplifying virtual knots and links.
method Introducing a new local deformation called the virtualized Δ-move.
result Virtualized Δ-move is an unknotting operation for virtual knots.
Forbidden detour moves unknot virtual knots.
problem Unknotting virtual knots using forbidden detour moves.
method Introduced forbidden detour moves as an unknotting operation for virtual knots and defined the forbidden detour number.
result Upper and lower bounds on the forbidden detour number are given in terms of knot invariants.
New presentations of a link and a virtual link are introduced and algebraic systems on links and virtual links are constructed respectively. Based on the algebraic systems, Reduction Crossing Algorithms for them are proposed which are used to reduce the number of crossings in a link and virtual link. For known unknots,…
New invariants show stronger virtual knot sets.
problem Classifying virtual knots using invariants.
method Defining -order invariants using forbidden moves.
result Set of -order invariants is strictly stronger.
We define the virtual bridge number and the virtual unknotting number invariants for virtual knots. For ordinary knots they are closely related to the bridge number and the unknotting number and we have There are no ordinary knots with We…
Defines new invariant for virtual knots.
problem Determining unknottability of virtual knots.
method Parity virtual Alexander polynomial.
result Many virtual knots cannot be unknotted by odd crossing changes.
New invariant measures how many twists are needed to unknot welded knots.
problem Measuring complexity of welded knots.
method Local twist move, Alexander quandle coloring, Gordian distance.
result Established lower bound on twist number and related it to other knot invariants.
A pseudodiagram is a diagram of a knot with some crossing information missing. We review and expand the theory of pseudodiagrams introduced by R. Hanaki. We then extend this theory to the realm of virtual knots, a generalization of knots. In particular, we investigate how much crossing information must be known to conc…
The forbidden moves can be combined with Gauss diagram Reidemeister moves to obtain move sequences with which we may change any Gauss diagram (and hence any virtual knot) into any other, including in particular the unknotted diagram
The paper classifies virtual links using the arc shift operation.
problem Classifying \( n \)-component virtual links up to arc shift equivalence.
method Established the arc shift operation as an unknotting tool for \( n \)-homogeneous proper virtual links, explored its connection to the odd writhe, and identified sequences with specific arc shift bounds.
result Identified sequences of virtual link diagrams \( L_n \) with an upper bound of arc shift number equal to \( n \).
We introduce a notion of intrinsic linking and knotting for virtual spatial graphs. Our theory gives two filtrations of the set of all graphs, allowing us to measure, in a sense, how intrinsically linked or knotted a graph is; we show that these filtrations are descending and non-terminating. We also provide several ex…
The paper calculates the slice genus for many virtual knots.
problem Determining which virtual knots are slice.
method Computing Turaev's graded genus and developing an algorithm for virtual unknotting operations.
result Many virtual knots with 6 or fewer crossings are slice.
New moves transform any virtual knot to a trivial knot.
problem Transforming virtual knots to trivial knots.
method Introducing arc shift and region arc shift moves.
result Any virtual knot can be transformed into a trivial knot using these moves.
The paper studies generalized virtualization moves on welded links and classifies their equivalence.
problem Classifying equivalence of welded links under specific moves.
method Introduced and analyzed two new moves, and , on welded links.
result The -move is an unknotting operation for any , while is not for .
Every classical knot is band-pass equivalent to the unknot or the trefoil. The band-pass class of a knot is a concordance invariant. Every ribbon knot, for example, is band-pass equivalent to the unknot. Here we introduce the long virtual knot concordance group . It is shown that for every concordance cla…
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 {\it forbidden number}. We relate the forbidden number to several known invarian…
Kishino's knot is not detected by the fundamental group or the bracket polynomial; these invariants cannot differentiate between Kishino's knot and the unknot. However, we can show that Kishino's knot is not equivalent to unknot by applying either the 3-strand bracket polynomial or the surface bracket polynomial. In th…
We claim that HOMFLY polynomials for virtual knots, defined with the help of the matrix-model recursion relations, contain more parameters, than just the usual and . These parameters preserve topological invariance and do not show up in the case of ordinary (non-virtual) knots and links. They are most conv…
ReAPR simplifies hard unknots by reembedding and rerouting, revealing hidden simplifications.
problem Training AI to recognize knots, especially hard unknots, is challenging.
method Alternates pass-move reduction with geometric re-embedding, minimizing total variation of a height function.
result ReAPR successfully simplifies hard unknots, including Kauffman's challenge unknots, in under 30 seconds.
The paper introduces a new filtration for knot invariants and proves the existence of nontrivial knots.
problem The existence of nontrivial knots with specific invariant properties.
method Definition of F-order and n-triviality via virtualization and forbidden moves.
result Existence of infinitely many nontrivial classical knots and a nontrivial virtual knot with specific invariant properties.
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 biquandles are studied. These invariants are applied to show the non-existence of Al…
In this paper we define and give examples of a family of polynomial invariants of virtual knots and links. They arise by considering certain 22 matrices with entries in a possibly non-commutative ring, for example the quaternions. These polynomials are sufficiently powerful to distinguish the Kishino knot from …
The paper studies unknotting operations and numbers for plus-welded knotoids.
problem Understanding unknotting operations and numbers for plus-welded knotoids.
method The paper proves transformations and introduces new operations to calculate unknotting numbers.
result Upper bounds for unknotting numbers of plus-welded knotoids are found.
CF-moves for virtual linksmath.GT
The paper extends CF-moves to classify virtual links of any number of components.
problem Classifying virtual links using CF-moves.
method Extending CF-moves to classify virtual links of arbitrary number of components using the virtual linking number and invariants.
result Classification of 3-component even virtual links up to CF-moves.
New groups from virtual link stacks distinguish Kishino knots.
problem Detecting and distinguishing Kishino knots from the unknot and from each other.
method Constructing groups from virtual link stacks and using them to distinguish knots.
result The groups constructed using this method distinguish all Kishino knots from the unknot and from each other.
Category theory generalizes finite type invariants using diagrams systems.
problem Generalizing finite type invariants using category theory.
method Relating generating sets for generalized finite type theories with diagrams systems.
result Demonstrates the correspondence between finite type theories and diagrams systems.
All knots are fused isotopic to the unknot via a process known as virtualization. We extend and adapt this process to show that, up to fused isotopy, classical links are classified by their linking numbers.
Forbidden moves categorify fused links into quivers.
problem Categorify fused links to invariant of links.
method Use forbidden moves to categorify fused links.
result Obtain three polynomial invariants of links.
Pseudodiagrams are knot or link diagrams where some of the crossing information is missing. Pseudoknots are equivalence classes of pseudodiagrams, where equivalence is generated by a natural set of Reidemeister moves. In this paper, we introduce a Gauss-diagrammatic theory for pseudoknots which gives rise to the notion…
New moves help untangle complex knots.
problem Deforming twisted knots into simpler forms.
method Finite sequences of extended Reidemeister moves and three forbidden moves.
result Any twisted knot can be simplified.
Doubled Khovanov Homologymath.GT
We define a homology theory of virtual links built out of the direct sum of the standard Khovanov complex with itself, motivating the name doubled Khovanov homology. We demonstrate that it can be used to show that some virtual links are non-classical, and that it yields a condition on a virtual knot being the connect s…
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 examples of welded knots which are shown to be non-trivial by the new invariants. Thes…
Unified proof of knot unknotting bounds using Ma-Qiu index.
problem Finding bounds on the number of moves to unknot knots.
method Using the Ma-Qiu index to bound presentation distances and Gordian distances.
result Unified proof of various unknotting number bounds.
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 examples of welded knots which are shown to be non-trivial by the new invariants. Thes…
Virtual knot invariants are linked to link invariants in 3D space.
problem Relating virtual knot invariants to link invariants in 3D space.
method Virtual covers and fiber stabilization techniques.
result Alexander polynomials of almost classical knots are specializations of multi-variable Alexander polynomials of certain links.
In the present paper, we consider local moves on classical and welded diagrams: (self-)crossing change, (self-)virtualization, virtual conjugation, Delta, fused, band-pass and welded band-pass moves. Interrelationship between these moves is discussed and, for each of these move, we provide an algebraic classification. …
Hard Legendrian unknotsmath.GT
Study on hard Legendrian unknots using normal rulings.
problem Understanding the complexity of Legendrian unknots in knot theory.
method Using normal rulings to obstruct and construct hard unknot diagrams.
result Construction of infinitely many smoothly hard max-tb unknot diagrams with bounds on minimum possible writhe.
New SCI index bounds unknotting framed unknots.
problem Bounding unknotting framed unknots.
method Introducing Self-Crossing Index (SCI) and using it to provide bounds.
result SCI provides bounds for unknotting framed unknots.
Agent finds unknotting sequences for complex knots.
problem Finding minimal crossing changes to unknot complex knots.
method Reinforcement learning agent for knot diagrams.
result Upper bounds on unknotting numbers for thousands of knots.
Proves Jones unknot conjecture for knots up to 23 crossings.
problem Verifying the Jones polynomial distinguishes the unknot from nontrivial knots.
method Analyzing Jones polynomials up to 23 crossings.
result Jones polynomial successfully distinguishes the unknot from nontrivial knots up to 23 crossings.
Study unknotting numbers of prime θ-curves up to 7 crossings.
problem Determine unknotting numbers for prime θ-curves.
method Subadditivity of unknotting numbers, non-overlapping set analysis, crossing changes, new methods for obstructing unknotting number 1.
result Exact unknotting numbers for all prime θ-curves up to 7 crossings.
The (ordinary) unknotting-number of 1-dimensional knots, which is defined by using the crossing-change, is a very basic and important invariant. It is very natural to consider the `unknotting-number' associated with other local-moves on n-dimensional knots, where n is a natural number. In this paper we prove the follow…