arXiv research

Paper characterizes links with same reduced peripheral system.

Ribbon 2-knotted objects are locally flat embeddings of surfaces in 4-space which bound immersed 3-manifolds with only ribbon singularities. They appear as topological realizations of welded knotted objects, which is a natural quotient of virtual knot theory. In this paper we consider ribbon tubes and ribbon torus-link…

We consider knotted annuli in 4-space, called 2-string-links, which are knotted surfaces in codimension two that are naturally related, via closure operations, to both 2-links and 2-torus links. We classify 2-string-links up to link-homotopy by means of a 4-dimensional version of Milnor invariants. The key to our proof…

Classifies colored links and spatial graphs up to colored link-homotopy.

New method classifies 4-component link homotopy using claspers.

It has long been known that a Milnor invariant with no repeated index is an invariant of link homotopy. We show that Milnor's invariants with repeated indices are invariants not only of isotopy, but also of self C_k-moves. A self C_k-move is a natural generalization of link homotopy based on certain degree k clasper su…

The paper classifies links up to link-homotopy using claspers.

We introduce the notion of quasi-triviality of quandles and define homology of quasi-trivial quandles. Quandle cocycle invariants are invariant under link-homotopy if they are associated with 2-cocycles of quasi-trivial quandles. We thus obtain a lot of numerical link-homotopy invariants.

Innovates a three-component link homotopy invariant.

New tribrackets defined to count link homotopy invariants.

Link homotopy has been an active area of research for knot theorists since its introduction by Milnor in the 1950s. We introduce a new equivalence relation on spatial graphs called component homotopy, which reduces to link homotopy in the classical case. Unlike previous attempts at generalizing link homotopy to spatial…

We investigate some algebraic structures called quasi-trivial quandles and we use them to study link-homotopy of pretzel links. Precisely, a necessary and sufficient condition for a pretzel link with at least two components being trivial under link-homotopy is given. We also generalize the quasi-trivial quandle idea to…

Two string links are equivalent up to $2n$-moves and link-homotopy if and only if their all Milnor link-homotopy invariants are congruent modulo $n$. Moreover, the set of the equivalence classes forms a finite group generated by elements of order $n$. The classification induces that if two string links are equivalent u…

New theory classifies knotted spheres in 4D space.

Defines new link-homotopy invariants using Milnor's higher order link invariants.

The theory of link-homotopy, introduced by Milnor, is an important part of the knot theory, with Milnor's mu-bar-invariants being the basic set of link-homotopy invariants. Skein relations for knot and link invariants played a crucial role in the recent developments of knot theory. However, while skein relations for Al…

Paper introduces new link homotopy invariants and applies them to 3-bouquet graphs.

We affirmatively address the question of whether the proposed link homotopy invariant $ω$ of Li is well-defined. It is also shown that if one wishes to adapt the homotopy invariant $τ$ of Schneiderman-Teichner to a link homotopy invariant of link maps, the result coincides with $ω$.

Extends Goldberg's result for string links over surfaces.

Bar-Natan used Chinese characters to show that finite type invariants classify string links up to homotopy. In this paper, I construct the correct spaces of chord diagrams and Chinese characters for links up to homotopy. I use these spaces to show that the only rational finite type invariants of link homotopy are the p…

We use a new geometric construction, grope splitting, to give a sharp bound for separation of surfaces in 4-manifolds. We also describe applications of this technique in link-homotopy theory, and to the problem of locating pi_1-null surfaces in 4-manifolds. In our applications to link-homotopy, grope splitting serves a…

Study of concordances between links in 4-space, defining new invariants.

An explicit polynomial in the linking numbers $l_{ij}$ and Milnor's triple linking numbers $μ(rst)$ on six component links is shown to be a well-defined finite type link-homotopy invariant. This solves a problem raised by B. Mellor and D. Thurston. An extension of our construction also produces a finite type link invar…

Two link diagrams are link homotopic if one can be transformed into the other by a sequence of Reidemeister moves and self crossing changes. Milnor introduced invariants under link homotopy called $\barμ$. Nanophrases, introduced by Turaev, generalize links. In this paper, we extend the notion of link homotopy to nanop…

Implemented Habegger-Lin algorithm for 4- and 5-component links.

The paper calculates actions of string link operations for 4- and 5-component links.

In a previous paper, the authors proved that Milnor link-homotopy invariants modulo $n$ classify classical string links up to $2n$-move and link-homotopy. As analogues to the welded case, in terms of Milnor invariants, we give here two classifications of welded string links up to $2n$-move and self-crossing virtualizat…

Paper defines linking numbers for periodic tangles.

This paper defines ribbons and ribbon complexes in CW spaces and analyzes their topological properties.

Formula for Alexander polynomials of simple-ribbon knots derived.

We define a notion of finite type invariants for links with a fixed linking matrix. We show that Milnor's triple link homotopy invariant is a finite type invariant, of type 1, in this sense. We also generalize the approach to Milnor's higher order homotopy invariants and show that they are also, in a sense, of finite t…

Generalizes ribbonness result for surface-links.

New bounds found for ribbon numbers of knots and links.

Link concordance equals homotopy for high-dimensional spheres.

Study on folded ribbon knots and their minimum length.

We study the ribbon discs that arise from a symmetric union presentation of a ribbon knot. A natural notion of symmetric ribbon number is introduced and compared with the classical ribbon number. We show that the gap between these numbers can be arbitrarily large by constructing an infinite family of ribbon knots with …

In this paper, we analyze the Bollobás and Riordan polynomial $\mathcal{R}$ for ribbon graphs with half-ribbons introduced in [Combinatorics, Probability and Computing 31, 507-549, 2022]. We prove the universality property of a multivariate version of $\mathcal{R}$ whereas $\mathcal{R}$ itself turns out to be universal…

New knots bound multiple non-isotopic ribbon disks.

Author provides an alternate proof of the free ribbon lemma.

Extends Heisenberg homology to ribbon graphs.

The paper calculates ribbon numbers for 12-crossing knots using Alexander polynomials.

Study Alexander polynomials of ribbon and virtual knots using ribbon's intrinsic singularity.

Study knots that divide ribbon knotted surfaces, computing their half ribbon genus and fusion number.

Ribbon cobordism forms a partial order in 3-manifolds.

New concept of quasi-ribbon surface-links simplifies complex surface-links.

Paper studies metric ribbon graphs and provides a recursion for their volumes.

Study shows not all ribbon knots can be symmetric unions.

Solves Skopenkov's problem on graph embedding criteria.