In this short note we use methods of Friedl, Livingston and Zentner to show that there are knots that are not algebraically concordant to a connected sum of positive and negative L-space knots.
We consider the question, asked by Friedl, Livingston and Zentner, of which sums of torus knots are concordant to alternating knots. After a brief analysis of the problem in its full generality, we focus on sums of two torus knots. We describe some effective obstructions based on Heegaard Floer homology.
下面是一个长期存在的开放问题:“如果在三维球面上的两个纽结上的零框架手术是整同调共边的,那么纽结本身是一致的吗?“我们表明,这个问题的一个明显的理性版本有一个否定的答案。也就是说,我们给出了节点的例子,它们的零框架手术是有理同调协边3-流形,其中节点不是有理协调的(即在任何有理同调S^3 x [0,1]中都不是协调的)。具体地说,我们证明了对任意正整数p和任意纽结K,K上的零框架外科手术与其(p,1)cable上的零框架外科手术是Z[1/p]-同调协边的.然后,我们观察到,大多数纽结是不合理的协调,他们的(p,1)电缆。
We give an infinite family of knots that are not rationally concordant to their reverses. More precisely, if R denotes the involution of the rational knot concordance group QC induced by string reversal and Fix(R) denotes the subgroup of knots fixed under R in QC, then QC/Fix(R) contains an infinite rank subgroup. As a corollary, we show that there exists a knot K such that for every pair of coprime integers p and q, the (p,q)-cable of K is not concordant to the reverse of the (p,q)-cable of K.
Two knots are homology concordant if they are smoothly concordant in a homology cobordism. The group $\hat{\mathcal{C}}_{\mathbb{Z}}$ (resp. $\mathcal{C}_{\mathbb{Z}}$) was previously defined as the set of knots in homology spheres that bounds homology balls (resp. in $S^3$), modulo homology concordance. We prove $\hat{\mathcal{C}}_{\mathbb{Z}} / \mathcal{C}_{\mathbb{Z}}$ contains a $\mathbb{Z}^{\infty}$ subgroup. We construct our family of examples by applying the filtered mapping cone formula to $L$--space knots, and prove linear independence with the help of the connected knot complex.
It is known that connected sums of positive torus knots are not concordant to $L$-space knots. Here we consider differences of torus knots. The main result states that the subgroup of the concordance group generated by two positive torus knots contains no nontrivial $L$-space knots other than the torus knots themselves. Generalizations to subgroups generated by more than two torus knots are also considered.
For a knot in the 3-sphere, the Upsilon invariant is a piecewise linear function defined on the interval [0,2]. For an L-space knot, the Upsilon invariant is determined only by the Alexander polynomial of the knot. We exhibit infinitely many pairs of hyperbolic L-space knots such that two knots of each pair have distinct Alexander polynomials, so they are not concordant, but share the same Upsilon invariant. Conversely, we examine the restorability of the Alexander polynomial of an L-space knot from the Upsilon invariant through the Legendre-Fenchel transformation.
We show that the difference between the topological 4-genus of a knot and the minimal genus of a surface bounded by that knot that can be decomposed into a smooth concordance followed by an algebraically simple locally flat surface can be arbitrarily large. This extends work of Hedden-Livingston-Ruberman showing that there are topologically slice knots which are not smoothly concordant to any knot with trivial Alexander polynomial.
For all n > 0 there is a homomorphism from the smooth concordance group of knots in dimension 2n + 1 to an algebraically defined group called the rational algebraic concordance group. This algebraic concordance group splits as a direct sum of groups indexed by polynomials. For n > 1 the homomorphism is injective. This leads to what is called a primary decomposition theorem for knot concordance. In the classical dimension, the kernel of this homomorphism includes the smooth concordance group of topologically slice knots, and Jae Choon Cha has begun studying possible primary decompositions of th…
We give a formula of the Upsilon invariant of any L-space cable knot $K_{p,q}$ using $p,Υ_K$ and $Υ_{T_{p,q}}$. The integral value of the Upsilon invariant gives a ${\mathbb Q}$-valued knot concordance invariant. We compute the integral values for L-space iterated cable knots.
The concepts of tile number and space-efficiency for knot mosaics were first explored by Heap and Knowles (arXiv:1702.06462), where they determined the possible tile numbers and space-efficient layouts for every prime knot with mosaic number 6 or less. In this paper, we extend those results to prime knots with mosaic number 7.
Greene, Lewallen and Vafaee characterized $(1,1)$ L-space knots in $S^3$ and lens space in the notation of coherent reduced $(1,1)$-diagrams. We analyze these diagrams, and deduce an explicit description of these knots. With the new description, we prove that any L-space obtained by Dehn surgery on a $(1,1)$-knot in $S^3$ has non-left-orderable fundamental group.
我们提出了一种S^1 x S^2中的纽结分类,允许对透镜空间进行纵向手术。通过对S^1 x S^2中的某些结进行纵向手术而获得的任何透镜空间,都可以从S^1 x S^2的Heegaard实心环面中的Berge-Gabai结获得,正如拉斯穆森所观察到的那样。我们发现,还有另外两个家庭的结:那些躺在纤维属一个纤维结和“零星”结。S^1 x S^2中的所有这些纽结都是双本原的和球形的辫子。这种分类源于对贝尔热在S ^3中的双本原纽结列表的推广,尽管我们也研究了如何使用Lisca对以透镜空间为界的有理同调球的交格的嵌入作为指导来发展它。我们猜想,我们的结构成了S^1 × S^2中双本原结的一个完整列表,并把这个猜想归结为对允许纵向S^1 × S^2手术的透镜空间中的结的同调类进行分类。
Let $D$ be a diagram of an alternating knot with unknotting number one. The branched double cover of $S^3$ branched over $D$ is an L-space obtained by half integral surgery on a knot $K_D$. We denote the set of all such knots $K_D$ by $\mathcal D$. We characterize when $K_D\in \mathcal D$ is a torus knot, a satellite knot or a hyperbolic knot. In a different direction, we show that for a given $n>0$, there are only finitely many L-space knots in $\mathcal D$ with genus less than $n$.
在本文中,我们介绍了一个空间有效的节点马赛克的概念。也就是说,我们试图确定如何使用最少数量的非空白瓷砖来描绘结。这个最小的数称为节点的瓦片数。我们确定严格的界限的瓷砖数的一个结的马赛克数的结。特别地,如果$t$是具有马赛克编号$m$的素结的瓦片编号,则如果$m$是偶数则为$5m-8 \leq t \leq m^2-4$,并且如果$m$是奇数则为$5m-8 \leq t \leq m^2-8$。我们还确定了几个节点的瓷砖数量,并为每个节点提供了空间有效的节点马赛克。