Ka Yi Ng
Dror Bar-Natan and Ofer Ron have questioned the accuracy of the statement on page 453, line 2 minus of my paper "Groups of Ribbon Knots", Topology Vol 37, No. 2, 441-458, that "It follows from the inductive proof that $\cal{R}_n$ is of index 2." See their article posted on arXiv: math.GT/0309282. We give here full details of how to carry out the inductive step.
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The present paper is an addendum to "Spherical structures on torus knots and links", arXiv:1008.0312, and concerns more general case of torus knot and link cone-manifolds.
We observe that the main theorem in \cite{KMsuture} immediately implies its analogue for closed 3--manifolds.
This paper was withdrawn by the author. The appearance of an author-written addendum [3] to the paper [2] made our correction note [1] to that paper superfluous and hence it is no longer available here. [1] Dror Bar-Natan and Ofer Ron, A Correction to "Groups of Ribbon Knots" by Ka Yi Ng, no longer available. [2] Ka Yi Ng, Groups of Ribbon Knots, Topology 37 (1998) 441-458. [3] Ka Yi Ng, Addendum to "Groups of Ribbon Knots", arXiv:math.GT/0310074.
Knotted ribbons form an important topic in knot theory. They have applications in natural sciences, such as cyclic duplex DNA modeling. A flat knotted ribbon can be obtained by gently pulling a knotted ribbon tight so that it becomes flat and folded. An important problem in knot theory is to study the minimal ratio of length to width of a flat knotted ribbon. This minimal ratio is called the ribbonlength of the knot. It has been conjectured that the ribbonlength has an upper bound and a lower bound which are both linear in the crossing number of the knot. In the first part of the paper, we use…
Alexander polynomials of simple-ribbon knots
本文给出了简单-带状纽结的亚历山大多项式公式，并利用该公式判定10交叉纽结是否为简单-带状纽结，同时提供了简单-带状纽结同时为m-和n-简单-带状纽结的条件。
A closer look at an example introduced by Livingston & Melvin and later studied by Miyazaki shows that a plumbing of two fibered ribbon knots (along their fiber surfaces) may be algebraically slice yet not ribbon.
This paper gives a new obstruction for ribbon-move equivalence of 2-knots. Let $K$ and $K'$ be 2-knots. Let $K$ and $K'$ are ribbon-move equivalent. One corollary to our main theorem is as follows. A 2-dimensional fibered knot whose fiber is the punctured 3-dimensional torus is not ribbon-move equivalent to any 2-dimensional knot whose Seifert hypersurface is a punctured homology sphere.
We show that every $\mathbb{Z}$-torsion free knot module is realized by a ribbon 2-knot with group of geometric dimension at most 2, and give some partial results on the characterization of the knot modules of fibred ribbon 2-knots.
This survey reviews Kauffman's model of folded ribbon knots: knots made of a thin strip of paper folded flat in the plane. The ribbonlength is the length to width ratio of such a ribbon, and the ribbonlength problem asks to minimize the ribbonlength for a given knot type. We give a summary of known results. For the most part, these are upper bounds of ribbonlength of twist knots and certain families of torus knots. We discuss result of G. Tian, which give upper bounds of ribbonlength in terms of crossing number. In addition, it turns out the choice of fold affects the ribbonlength. We end with…
Knot quandles distinguish Suciu's ribbon knots
本文研究Suciu带状n-纽结的纽结quandle，证明尽管这些纽结的纽结群同构，其纽结quandle仍彼此不同构，并进一步计算了这些quandle的类型。
We study Kauffman's model of folded ribbon knots: knots made of a thin strip of paper folded flat in the plane. The ribbonlength is the length to width ratio of such a folded ribbon knot. We show for any knot or link type that there exist constants $c_1, c_2>0$ such that the ribbonlength is bounded above by $c_1\cdot Cr(K)^2$, and also by $c_2\cdot Cr(K)^{3/2}$. We use a different method for each bound. The constant $c_1$ is quite small in comparison to $c_2$, and the first bound is lower than the second for knots and links with $Cr(K)\leq$ 12,748.
A ribbon is a two-dimensional object with one-dimensional properties which is related with geometry, robotics and molecular biology. A folded ribbon structure provides a complex structure through a series of folds. We focus on a folded ribbon with knotted core. The folded ribbonlength $Rib(K)$ of a knot $K$ is the infimum of the quotient of length by width among the ribbons representing a knot type of $K$. This quantity tells how efficiently the folded ribbon is realized. Kusner conjectured that folded ribbonlength is bounded by a linear function of the minimal crossing number $c(K)$. In this …
Let $K, K'$ be ribbon knottings of $n$-spheres with $1$-handles in $S^{n+2}$, $n\geq 2$. We show that if the knot quandles of these knots are isomorphic, then the ribbon knottings are stably equivalent, in the sense of Nakanishi and Nakagawa, after taking a finite number of connected sums with trivially embedded copies of $S^{n-1}\times S^{1}$.
We consider ribbon n-knots for n\geq 2. For such knots we define a set of moves on ribbon disks, and show that any two ribbon disks for isotopic knots are related by a finite sequence of such moves and ambient isotopies. Using this we are able to prove that there is a natural geometric correspondence between ribbon n-knots and ribbon m-knots which is bijective. We also explore a diagrammatic calculus for such knots. In addition we show that for such knots, any two band presentations for the same knot are stably equivalent.
In this note we show that ribbon concordance forms a partial ordering on the set of knots, answering a question of Gordon. The proof makes use of representation varieties of the knot groups to $SO(N)$ and relations between them induced by a ribbon concordance.
On knots that divide ribbon knotted surfaces
本文研究了半带状结的 genus 和半融合数，计算了多个结的半带状 genus 并探讨了其与双可切 genus 的关系。
Ribbonlength upper bounds for small crossing knots and links
本文提出构造折叠带状纽结的新方法，改进了 $(2,q)$-环面链环、扭转纽结和椒盐卷饼链环的折叠带长上界，并给出八字结为 8 的构造与最优性猜想。
We establish the slice-ribbon conjecture for a large family of Montesinos' knots by means of Donaldson's theorem on the intersection forms of definite 4-manifolds.
Immersed flat ribbon knots
该研究通过将浸入式平面带状纽结链环空间嵌入圆盘图空间求解最小带长，给出反例与猜想，计算了部分小型及无限族链环图的最小带长，还得到了对应最小带长的图的交叉数界。
This paper gives mathematical models for flat knotted ribbons, and makes specific conjectures for the least length of ribbon (for a given width) needed to tie the trefoil knot and the figure eight knot. The first conjecture states that (for width one) the least length of ribbon needed to tie an open-ended trefoil knot is L = 4(F + 1)/Sqrt[2 + F] where F = (1 + Sqrt[5])/2 is the golden ratio. The second conjecture states that the least length of the figure eight knot (in the same sense) is 32/Sqrt[15].
We prove that the map on knot Floer homology induced by a strongly homotopy-ribbon concordance is injective.
A ribbon knot which is not a symmetric union
针对带形纽结是否都能表示为对称并的问题，通过构造一个具体的带形Montesinos纽结，给出否定答案。
We prove that the map on knot Floer homology induced by a ribbon concordance is injective. As a consequence, we prove that the Seifert genus is monotonic under ribbon concordance. We also generalize a theorem of Gabai about the super-additivity of the Seifert genus under band connected sum. Our result gives evidence for a conjecture of Gordon that ribbon concordance is a partial order on the set of knots.
Ribbon numbers of 12-crossing knots
本文研究纽结的带状数，通过Alexander多项式集合计算12交叉纽结的带状数，并发现该方法对高亏格情形不再有效。
Profiles of Critical Flat Ribbon Knots
本文针对理想纽结例子稀缺的问题，计算了Salomon纽结、Turk's head纽结、granny纽结和square纽结等的最小带状长度，并给出无限类临界带状纽结的带状长度及与纽结不变量相关的猜想。
Ribbonlength of families of folded ribbon knots
本文研究折叠丝带结的丝带长度，给出多类结的线性上界，并构造(p,q)环面结的次线性上界，证明三叶结可用丝带长度6实现。
Linear Upper Bounds on the Ribbonlength of Knots and Links
本文通过二进制网格图和双倍顶点分级技术，证明了结和链的 ribbonlength 与交叉数之间存在线性上界关系。
We define an obstruction for a knot to be Z[Z]-homology ribbon, and use this to provide restrictions on the integers that can occur as the triple linking numbers of derivative links of knots that are either homotopy ribbon or doubly slice. Our main application finds new non-doubly slice knots. In particular this gives new information on the doubly solvable filtration of Taehee Kim: doubly algebraically slice ribbon knots need not be doubly (1)-solvable, and doubly algebraically slice knots need not be (0.5,1)-solvable. We also discuss potential connections to unsolved conjectures in knot conco…
The fusion number of a ribbon knot is the minimal number of 1-handles needed to construct a ribbon disk. The strong homotopy fusion number of a ribbon knot is the minimal number of 2-handles in a handle decomposition of a ribbon disk complement. We demonstrate that these invariants behave completely differently under cabling by showing that the (p,1)-cable of any ribbon knot with fusion number one has strong homotopy fusion number one and fusion number p. Our main tools are Juhász-Miller-Zemke's bound on fusion number coming from the torsion order of knot Floer homology and Hanselman-Watson's …
It is known that there are 21 ribbon knots with 10 crossings or fewer. We show that for every ribbon knot, there exists a tangle that satisfies two properties associated with the knot. First, under a specific closure, the closed tangle is equivalent to its corresponding knot. Second, under a different closure, the closed tangle is equivalent to the unlink. For each of these 21 ribbon knots, we present a 4-strand tangle that satisfies these properties. We provide diagrams of these tangles and also express them in planar diagram notation.
We describe an algorithm to find ribbon disks for alternating knots, and the results of a computer implementation of this algorithm. The algorithm is underlain by a slice link obstruction coming from Donaldson's diagonalisation theorem. It successfully finds ribbon disks for slice two-bridge knots and for the connected sum of any alternating knot with its reverse mirror, as well as for 662,903 prime alternating knots of 21 or fewer crossings. We also identify some examples of ribbon alternating knots for which the algorithm fails to find ribbon disks, though a related search identifies all suc…
Using Kauffman's model of flat knotted ribbons, we demonstrate how all regular polygons of at least seven sides can be realised by ribbon constructions of torus knots. We calculate length to width ratios for these constructions thereby bounding the Ribbonlength of the knots. In particular, we give evidence that the closed (respectively, truncation) Ribbonlength of a (q+1,q) torus knot is (2q+1)cot(π/(2q+1)) (resp., 2q cot(π/(2q+1))). Using these calculations, we provide the bounds c_1 \leq 2/πand c_2 \geq 5/3 cot(π/5) for the constants c_1 and c_2 that relate Ribbonlength R(K) and crossing num…
Ribbon concordance and the minimality of tight fibered knots
本文证明了所有紧纤维化纽结在带状合痕构成的偏序集中具有极小性，并给出了除8_15外至多8交叉的素极小纽结表。
We determine the smooth concordance order of the 3-stranded pretzel knots P(p,q,r) with p,q,r odd. We show that each one of finite order is, in fact, ribbon, thereby proving the slice-ribbon conjecture for this family of knots. As corollaries we give new proofs of results first obtained by Fintushel-Stern and Casson-Gordon.
On two-bridge ribbon knots
本文证明双桥带状纽结 $K(m^2, m k \pm 1)$ 可表示为以双桥纽结 $K(m,k)$ 为部分纽结的对称并集，并推广至所有此类纽结。
Ribbon concordance of fibered knots and compressions of surface homeomorphisms
研究证明纤维结在丝带同调下单纯体积和扩张率单调，并提供算法用于寻找强同伦丝带同调与给定纤维结相关的结，同时扩展了Casson--Long的定理。
We prove that all 2-bridge ribbon knots are symmetric unions.
Non-triviality of welded knots and ribbon torus-knots
本文通过焊接经典纽结图中的交叉点构造焊接纽结，并利用基本群证明其非平凡性，从而给出非平凡带状环面的例子。
Ribbon knots and iterated cables of fibered knots
本文利用有边 Heegaard Floer 同调中的 $γ_0$ 不变量刻画 $γ_0$-sharp 纤维纽结连通和的带状性，并据此推出紧纤维纽结迭代缆线的线性无关性或切片–带状猜想失败。
Linking number and folded ribbon unknots
本文研究Kauffman折叠带状纽结模型，确定了特定环绕数下3段解结的最小折叠带状长度，并证明钝角n边形在正则时达到最小折叠带状长度，同时给出拓扑圆环面折叠带状解结的最小折叠带状长度上界为2n。
A pretzel knot $K$ is called $odd$ if all its twist parameters are odd, and $mutant$ $ribbon$ if it is mutant to a simple ribbon knot. We prove that the family of odd, 5-stranded pretzel knots satisfies a weaker version of the Slice-Ribbon Conjecture: All slice, odd, 5-stranded pretzel knots are $mutant$ $ribbon$. We do this in stages by first showing that 5-stranded pretzel knots having twist parameters with all the same sign or with exactly one parameter of a different sign have infinite order in the topological knot concordance group, and thus in the smooth knot concordance group as well. N…
We present the results of Axel Seeliger's tabulation of symmetric union presentations for ribbon knots with crossing numbers 11 and 12 and exhibit possible examples for ribbon knots which are not representable as symmetric unions. In addition, we give a complete atlas of band diagrams for prime ribbon knots with 11 and 12 crossings.
Ribbon concordance and cabling
本文提出关于 ribbon concordance 与缆化纽结的猜想，证明其在特定情形成立，运用纽结 Floer 同调的最小高度不变量，还得到相关亏格界，为纽结理论研究提供新结论。
Akbulut and Kirby conjectured that two knots with the same $0$-surgery are concordant. In this paper, we prove that if the slice-ribbon conjecture is true, then the modified Akbulut-Kirby's conjecture is false. We also give a fibered potential counterexample to the slice-ribbon conjecture.
Knots bounding non-isotopic ribbon disks
本文构造无穷多个带形纽结，每个界定无穷多个外部微分同胚但两两非同位的带形圆盘，并给出广义方结的纤维化同伦带形圆盘的合痕分类，肯定回答了 Hitt 和 Sumners 问题的加强版本。
The stable Kauffman conjecture posits that a knot in $S^3$ is slice if and only if it admits a slice derivative. We prove a related statement: A knot is handle-ribbon (also called strongly homotopy-ribbon) in a homotopy 4-ball $B$ if and only if it admits an R-link derivative; i.e. an $n$-component derivative $L$ with the property that zero-framed surgery on $L$ yields $\#^n(S^1\times S^2)$. We also show that $K$ bounds a handle-ribbon disk $D \subset B$ if and only if the 3-manifold obtained by zero-surgery on $K$ admits a singular fibration that extends over handlebodies in $B \setminus D$, …
Ribbon concordance and fibered predecessors
本研究证明三维球面中任意纽结的带状和谐双曲纤维化纽结及纤维化纽结的带状和谐双曲前继均有限，结合Floer同调与单值群性质完成证明，并推导了这类纽结的体积不等式。
Symmetric ribbon numbers of low-complexity knots
本文系统研究了最多12个交叉点的纽结的对称带数，通过纽结行列式、Alexander多项式、Jones多项式和Kauffman多项式给出了新的下界。
Positive Knots and Ribbon Concordance
本文证明正纽结在带子配边偏序中是最小元且不能表示为非平凡带和，推广了特殊交错纽结的相关定理，并证明配边正纽结在特定条件下具有同构的有理Alexander模，支持每个配边类至多含一个正纽结的猜想。
We study the relationship between fibered ribbon 1-knots and fibered ribbon 2-knots by studying fibered slice disks with handlebody fibers. We give a characterization of fibered homotopy-ribbon disks and give analogues of the Stallings twist for fibered disks and 2-knots. As an application, we produce infinite families of distinct homotopy-ribbon disks with homotopy equivalent exteriors, with potential relevance to the Slice-Ribbon Conjecture. We show that any fibered ribbon 2-knot can be obtained by doubling infinitely many different slice disks (sometimes in different contractible 4-manifold…
Kjuchukova's $Ξ_p$ invariant gives a ribbon obstruction for Fox $p$-colored knots. The invariant is derived from dihedral branched covers of 4-manifolds, and is needed to calculate the signatures of these covers, when singularities on the branching sets are present. In this note, we give an algorithm for evaluating $Ξ_p$ from a colored knot diagram, and compute a couple of examples.
The twisting number of a ribbon knot is bounded below by its doubly slice genus
该研究证明带状纽结的扭转数以双重切片亏格为下界，构造出扭转数任意高的带状纽结解决Tanaka的问题，并确定了部分12交叉纽结的未知双重切片亏格。
Bounding the ribbon numbers of knots and links
本文为带状纽结的带状数建立新下界，证明相关 Alexander 多项式集合有限可计算，并确定低阶情形，进而计算 11 交叉点以内带状纽结的带状数，同时给出链环的 Jones 多项式下界。
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 following facts. For the ribbon-move on 2-knots, which is a kind of local-move on knots, we have the following: There is a ribbon-move-unknotting-number-two 2-knot. The ribbon-move-unknotting-number of 2-knots is unbounded. For the pass-move on 1-knots, which is a kind of local-move on…
A ribbon is, intuitively, a smooth mapping of an annulus $S^1 \times I$ in 3-space having constant width $\varepsilon$. This can be formalized as a triple $(x,\varepsilon, \mathbf{u})$ where $x$ is smooth curve in 3-space and $\mathbf{u}$ is a unit vector field based along $x$. In the 1960s and 1970s, G. Calugareanu, G. H. White, and F. B. Fuller proved relationships between the geometry and topology of thin ribbons, in particular the "Link = Twist + Writhe" theorem that has been applied to help understand properties of double-stranded DNA. Although ribbons of small width have been studied ext…
Kanenobu has given infinite families of knots with the same HOMFLY polynomials. We show that these knots also have the same sl(n) and HOMFLY homologies, thus giving the first example of an infinite family of knots undistinguishable by these invariants. This is a consequence of a structure theorem about the homologies of knots obtained by twisting up the ribbon of a ribbon knot with one ribbon.
In Theorem 1.2 of the paper math.GT/0002110 the author claimed to have proved that all transversal knots whose topological knot type is that of an iterated torus knot (we call them cable knots) are transversally simple. That theorem is false, and the Erratum math.GT/0610565 identifies the gap. The purpose of this paper is to explore the situation more deeply, in order to pinpoint exactly which cable knots are {\it not} transversally simple. The class is subtle and interesting. We will recover the strength of the main theorem in math.GT/0002110, in the sense that we will be able to prove a stro…
For knots in $S^3$, it is well-known that the Alexander polynomial of a ribbon knot factorizes as $f(t)f(t^{-1})$ for some polynomial $f(t)$. By contrast, the Alexander polynomial of a ribbon $2$-knot is not even symmetric in general. Via an alternative notion of ribbon $2$-knots, we give a topological condition on a $2$-knot that implies the factorization of the Alexander polynomial.
There is a question asking whether a handle-irreducible summand of every stable-ribbon surface-link is a unique ribbon surface-link. This question for the case of a trivial surface-link is affirmatively answered. That is, a handle-irreducible summand of every stably trivial surface-link is only a trivial 2-link. By combining this result with an old result of F. Hosowaka and the author that every surface-knot with infinite cyclic fundamental group is a stably trivial surface-knot, it is concluded that every surface-knot with infinite cyclic fundamental group is a trivial (i.e., an unknotted) su…
We show that if $K$ is a fibered ribbon knot in $S^3=\partial B^4$ bounding a ribbon disk $D$, then given an extra transversality condition the fibration on $S^3\setminusν(K)$ extends to a fibration of $B^4\setminusν(D)$. This partially answers a question of Casson and Gordon. In particular, we show the fibration always extends when $D$ has exactly two local minima. More generally, we construct movies of singular fibrations on $4$-manifolds and describe a sufficient property of a movie to imply the underlying $4$-manifold is fibered over $S^1$.
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