We introduce an equivalence relation, called stable equivalence, on knot diagrams and closed curves on surfaces. We give bijections between the set of abstract knots, the set of virtual knots, and the set of the stable equivalence classes of knot diagrams on surfaces. Using these bijections, we define concordance and link homology for virtual links. As an application, it is shown that Kauffman's example of a virtual knot diagram is not equivalent to a classical knot diagram.
We review some recent results in knot concordance and homology cobordism. The proofs rely on various forms of Heegaard Floer homology. We also discuss related open problems.
We consider free symmetries on cobordisms between knots. We classify which freely periodic knots bound equivariant surfaces in the 4-ball in terms of corresponding homology classes in lens spaces. A key tool is the homology cobordism classification of lens spaces using d-invariants. We give a numerical condition determining the free periods for which torus knots bound equivariant surfaces in the 4-ball.
We construct an invariant of virtual knots which is a sliceness obstruction and sensitive to the $Δ$-move. This invariants works if $\Z_{2}\oplus \Z_{2}$-index of chords is present.
The $0$-surgeries of two knots $K_1$ and $K_2$ are homology cobordant rel meridians if there exists a $\mathbb{Z}$-homology cobordism $X$ between them such that the two knot meridians are in the same homology class in $H_{1}(X,\mathbb{Z})$. In this paper, we give a pair of rationally slice knots which are not smoothly concordant but whose $0$-surgeries are homology cobordant rel meridians. One knot in the pair is the figure eight knot, which has concordance order two; all previous examples of such pairs of knots are infinite order.
For a connected cobordism S between two knots K1,K2 in S3, we establish an inequality involving the number of local maxima, the genus of S, and the torsion orders of Kht(K1),Kht(K2), where Kht denotes Lee's perturbation of Khovanov homology. This shows that the torsion order gives a lower bound for the band-unlinking number.
Given a connected cobordism between two knots in the 3-sphere, our main result is an inequality involving torsion orders of the knot Floer homology of the knots, and the number of local maxima and the genus of the cobordism. This has several topological applications: The torsion order gives lower bounds on the bridge index and the band-unlinking number of a knot, the fusion number of a ribbon knot, and the number of minima appearing in a slice disk of a knot. It also gives a lower bound on the number of bands appearing in a ribbon concordance between two knots. Our bounds on the bridge index a…
The cobordism distance between knots, d(K,J), equals the four-genus g_4(K # -J). We consider d(K,K^r), where K^r is the reverse of K. It is elementary that 0 \le d(K,K^r) \le 2g_4(K) and it is known that there are knots K for which d(K,K^r) is arbitrarily large. Here it is shown that for any knot for which g_4(K) = g_3(K) (such as non-slice knots with g_3(K) = 1 or strongly quasi-positive knots), one has that d(K,K^r) is strictly less that twice g_4(K). It is shown that for arbitrary positive g, there exist knots for which d(K,K^r) = g = g_4(K). There are no known examples for which d(K,K^r) >…
Let $\widehat{\mathcal{C}}_{\mathbb{Z}}$ denote the group of knots in homology spheres that bound homology balls, modulo smooth concordance in homology cobordisms. Answering a question of Matsumoto, the second author previously showed that the natural map from the smooth knot concordance group $\mathcal{C}$ to $\widehat{\mathcal{C}}_{\mathbb{Z}}$ is not surjective. Using tools from Heegaard Floer homology, we show that the cokernel of this map, which can be understood as the non-locally-flat piecewise-linear concordance group, is infinitely generated and contains elements of infinite order.
On Khovanov's cobordism theory for su(3) knot homology
本文重新考虑了Khovanov在Math.QA/0304375中定义的su（3）链同调论，以及Mackaay和Vaz在Math.GT/0603307中推广的su（3）链同调论.稍加修改后，我们将该理论描述为从缠结的平面代数到“有缝协边”（实际上是“cobordisms with seams”）（复合体）的平面代数（实际上是一个“canopolis”）的映射，使其在Bar-Natan的局部su（2）数学理论的意义上成为局部的。GT/0410495。我们表明，这种“有缝协边主义canopolis”decegorifies给正是你希望和期望：Kuperberg的su（3）蜘蛛在q-alg/9712003中定义。我们猜想一个答案，一个更有趣的问题，我们的配边理论的Karoubi信封的decategorification。最后，我们描述了如何理论实际上是完全可计算的，并给出了（2，n）环面结的su（3）同调的详细计算。
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。
Khovanov Homology, Lee Homology and a Rasmussen Invariant for Virtual Knots
本文包含了一个基本上自足的治疗Khovanov同调，Khovanov-Lee同调以及Rasmussen不变量的虚拟结和虚拟结配边，直接适用于经典的结和经典的结配边。要做到这一点，我们给出了一个替代配方的Manturov定义的Khovanov同调的虚拟结和链接与任意系数。这种方法使用纽结图上的切割轨迹来诱导Frobenius代数中的共轭算子。然后，我们讨论的影响，在上述理论的通用Frobenius代数的虚拟节点诱导的地图。接下来，我们将展示如何应用Karoubi包络的方法Bar-Natan和莫里森抽象的链接图与横截构建规范的Khovanov-李同源发电机。使用这些典型的发电机，我们推导出一个推广的Rasmussen不变量的虚拟结配边，并进一步推广Rasmussen的结果切片属正结的情况下，积极的虚拟结。还应该注意的是，这种推广的拉斯穆森不变量提供了一个很容易计算的障碍，在$S_g \times I \times I$的纽结配边在Turaev的意义。
Continuing our previous work, we effectively compute connected Heegaard Floer homologies of two families of Brieskorn spheres realized as the boundaries of almost simple linear graphs. Using Floer theoretic invariants of Dai, Hom, Stoffregen, and Truong, we show that these Brieskorn spheres also generate infinite rank summands in the homology cobordism group. Our computations also have applications to the concordance of classical knots and $0$-concordance of $2$-knots.
Dissolving knot surgered 4-manifolds by classical cobordism arguments
本文的目的是证明经典的协边论，它可以追溯到Mandelbaum和Moishezon的开创性工作，提供了任何纽结超紧单连通4-流形X_K在一个单一的稳定化后通过连接求和S^2 x S^2或CP^2 # -CP^2而成为同构于X的快速和统一的证明，对于许多几乎完全可分解的X，如椭圆曲面，X_K是几乎完全可分解的.
We show that the cobordism maps on Khovanov homology can distinguish smooth surfaces in the 4-ball that are exotically knotted (i.e., isotopic through ambient homeomorphisms but not ambient diffeomorphisms). We develop new techniques for distinguishing cobordism maps on Khovanov homology, drawing on knot symmetries and braid factorizations. We also show that Plamenevskaya's transverse invariant in Khovanov homology is preserved by maps induced by positive ascending cobordisms.
