Mutant Knots and Intersection Graphs 1 Introduction
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Oriented Pair (S 3,S1); Two Knots Are Regarded As
S-EQUIVALENCE OF KNOTS C. KEARTON Abstract. S-equivalence of classical knots is investigated, as well as its rela- tionship with mutation and the unknotting number. Furthermore, we identify the kernel of Bredon’s double suspension map, and give a geometric relation between slice and algebraically slice knots. Finally, we show that every knot is S-equivalent to a prime knot. 1. Introduction An oriented knot k is a smooth (or PL) oriented pair S3,S1; two knots are regarded as the same if there is an orientation preserving diffeomorphism sending one onto the other. An unoriented knot k is defined in the same way, but without regard to the orientation of S1. Every oriented knot is spanned by an oriented surface, a Seifert surface, and this gives rise to a matrix of linking numbers called a Seifert matrix. Any two Seifert matrices of the same knot are S-equivalent: the definition of S-equivalence is given in, for example, [14, 21, 11]. It is the equivalence relation generated by ambient surgery on a Seifert surface of the knot. In [19], two oriented knots are defined to be S-equivalent if their Seifert matrices are S- equivalent, and the following result is proved. Theorem 1. Two oriented knots are S-equivalent if and only if they are related by a sequence of doubled-delta moves shown in Figure 1. .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .. .... .... .... .... .... .... .... .... .... ... -
Deep Learning the Hyperbolic Volume of a Knot Arxiv:1902.05547V3 [Hep-Th] 16 Sep 2019
Deep Learning the Hyperbolic Volume of a Knot Vishnu Jejjalaa;b , Arjun Karb , Onkar Parrikarb aMandelstam Institute for Theoretical Physics, School of Physics, NITheP, and CoE-MaSS, University of the Witwatersrand, Johannesburg, WITS 2050, South Africa bDavid Rittenhouse Laboratory, University of Pennsylvania, 209 S 33rd Street, Philadelphia, PA 19104, USA E-mail: [email protected], [email protected], [email protected] Abstract: An important conjecture in knot theory relates the large-N, double scaling limit of the colored Jones polynomial JK;N (q) of a knot K to the hyperbolic volume of the knot complement, Vol(K). A less studied question is whether Vol(K) can be recovered directly from the original Jones polynomial (N = 2). In this report we use a deep neural network to approximate Vol(K) from the Jones polynomial. Our network is robust and correctly predicts the volume with 97:6% accuracy when training on 10% of the data. This points to the existence of a more direct connection between the hyperbolic volume and the Jones polynomial. arXiv:1902.05547v3 [hep-th] 16 Sep 2019 Contents 1 Introduction1 2 Setup and Result3 3 Discussion7 A Overview of knot invariants9 B Neural networks 10 B.1 Details of the network 12 C Other experiments 14 1 Introduction Identifying patterns in data enables us to formulate questions that can lead to exact results. Since many of these patterns are subtle, machine learning has emerged as a useful tool in discovering these relationships. In this work, we apply this idea to invariants in knot theory. -
A Remarkable 20-Crossing Tangle Shalom Eliahou, Jean Fromentin
A remarkable 20-crossing tangle Shalom Eliahou, Jean Fromentin To cite this version: Shalom Eliahou, Jean Fromentin. A remarkable 20-crossing tangle. 2016. hal-01382778v2 HAL Id: hal-01382778 https://hal.archives-ouvertes.fr/hal-01382778v2 Preprint submitted on 16 Jan 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. A REMARKABLE 20-CROSSING TANGLE SHALOM ELIAHOU AND JEAN FROMENTIN Abstract. For any positive integer r, we exhibit a nontrivial knot Kr with r− r (20·2 1 +1) crossings whose Jones polynomial V (Kr) is equal to 1 modulo 2 . Our construction rests on a certain 20-crossing tangle T20 which is undetectable by the Kauffman bracket polynomial pair mod 2. 1. Introduction In [6], M. B. Thistlethwaite gave two 2–component links and one 3–component link which are nontrivial and yet have the same Jones polynomial as the corre- sponding unlink U 2 and U 3, respectively. These were the first known examples of nontrivial links undetectable by the Jones polynomial. Shortly thereafter, it was shown in [2] that, for any integer k ≥ 2, there exist infinitely many nontrivial k–component links whose Jones polynomial is equal to that of the k–component unlink U k. -
RASMUSSEN INVARIANTS of SOME 4-STRAND PRETZEL KNOTS Se
Honam Mathematical J. 37 (2015), No. 2, pp. 235{244 http://dx.doi.org/10.5831/HMJ.2015.37.2.235 RASMUSSEN INVARIANTS OF SOME 4-STRAND PRETZEL KNOTS Se-Goo Kim and Mi Jeong Yeon Abstract. It is known that there is an infinite family of general pretzel knots, each of which has Rasmussen s-invariant equal to the negative value of its signature invariant. For an instance, homo- logically σ-thin knots have this property. In contrast, we find an infinite family of 4-strand pretzel knots whose Rasmussen invariants are not equal to the negative values of signature invariants. 1. Introduction Khovanov [7] introduced a graded homology theory for oriented knots and links, categorifying Jones polynomials. Lee [10] defined a variant of Khovanov homology and showed the existence of a spectral sequence of rational Khovanov homology converging to her rational homology. Lee also proved that her rational homology of a knot is of dimension two. Rasmussen [13] used Lee homology to define a knot invariant s that is invariant under knot concordance and additive with respect to connected sum. He showed that s(K) = σ(K) if K is an alternating knot, where σ(K) denotes the signature of−K. Suzuki [14] computed Rasmussen invariants of most of 3-strand pret- zel knots. Manion [11] computed rational Khovanov homologies of all non quasi-alternating 3-strand pretzel knots and links and found the Rasmussen invariants of all 3-strand pretzel knots and links. For general pretzel knots and links, Jabuka [5] found formulas for their signatures. Since Khovanov homologically σ-thin knots have s equal to σ, Jabuka's result gives formulas for s invariant of any quasi- alternating− pretzel knot. -
Representations of Edge Intersection Graphs of Paths in a Tree Martin Charles Golumbic, Marina Lipshteyn, Michal Stern
Representations of Edge Intersection Graphs of Paths in a Tree Martin Charles Golumbic, Marina Lipshteyn, Michal Stern To cite this version: Martin Charles Golumbic, Marina Lipshteyn, Michal Stern. Representations of Edge Intersection Graphs of Paths in a Tree. 2005 European Conference on Combinatorics, Graph Theory and Appli- cations (EuroComb ’05), 2005, Berlin, Germany. pp.87-92. hal-01184396 HAL Id: hal-01184396 https://hal.inria.fr/hal-01184396 Submitted on 14 Aug 2015 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. EuroComb 2005 DMTCS proc. AE, 2005, 87–92 Representations of Edge Intersection Graphs of Paths in a Tree Martin Charles Golumbic1,† Marina Lipshteyn1 and Michal Stern1 1Caesarea Rothschild Institute, University of Haifa, Haifa, Israel Let P be a collection of nontrivial simple paths in a tree T . The edge intersection graph of P, denoted by EP T (P), has vertex set that corresponds to the members of P, and two vertices are joined by an edge if the corresponding members of P share a common edge in T . An undirected graph G is called an edge intersection graph of paths in a tree, if G = EP T (P) for some P and T . -
MUTATIONS of LINKS in GENUS 2 HANDLEBODIES 1. Introduction
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY Volume 127, Number 1, January 1999, Pages 309{314 S 0002-9939(99)04871-6 MUTATIONS OF LINKS IN GENUS 2 HANDLEBODIES D. COOPER AND W. B. R. LICKORISH (Communicated by Ronald A. Fintushel) Abstract. A short proof is given to show that a link in the 3-sphere and any link related to it by genus 2 mutation have the same Alexander polynomial. This verifies a deduction from the solution to the Melvin-Morton conjecture. The proof here extends to show that the link signatures are likewise the same and that these results extend to links in a homology 3-sphere. 1. Introduction Suppose L is an oriented link in a genus 2 handlebody H that is contained, in some arbitrary (complicated) way, in S3.Letρbe the involution of H depicted abstractly in Figure 1 as a π-rotation about the axis shown. The pair of links L and ρL is said to be related by a genus 2 mutation. The first purpose of this note is to prove, by means of long established techniques of classical knot theory, that L and ρL always have the same Alexander polynomial. As described briefly below, this actual result for knots can also be deduced from the recent solution to a conjecture, of P. M. Melvin and H. R. Morton, that posed a problem in the realm of Vassiliev invariants. It is impressive that this simple result, readily expressible in the language of the classical knot theory that predates the Jones polynomial, should have emerged from the technicalities of Vassiliev invariants. -
NP-Complete and Cliques
CSC373— Algorithm Design, Analysis, and Complexity — Spring 2018 Tutorial Exercise 10: Cliques and Intersection Graphs for Intervals 1. Clique. Given an undirected graph G = (V,E) a clique (pronounced “cleek” in Canadian, heh?) is a subset of vertices K ⊆ V such that, for every pair of distinct vertices u,v ∈ K, the edge (u,v) is in E. See Clique, Graph Theory, Wikipedia. A second concept that will be useful is the notion of a complement graph Gc. We say Gc is the complement (graph) of G = (V,E) iff Gc = (V,Ec), where Ec = {(u,v) | u,v ∈ V,u 6= v, and (u,v) ∈/ E} (see Complement Graph, Wikipedia). That is, the complement graph Gc is the graph over the same set of vertices, but it contains all (and only) the edges that are not in E. Finally, a clique K ⊂ V of G =(V,E) is said to be a maximal clique iff there is no superset W such that K ⊂ W ⊆ V and W is a clique of G. Consider the decision problem: Clique: Given an undirected graph and an integer k, does there exist a clique K of G with |K|≥ k? Clearly, Clique is in NP. We wish to show that Clique is NP-complete. To do this, it is convenient to first note that the independent set problem IndepSet(G, k) is very closely related to the Clique problem for the complement graph, i.e., Clique(Gc,k). Use this strategy to show: IndepSet ≡p Clique. (1) 2. Consider the interval scheduling problem we started this course with (which is also revisited in Assignment 3, Question 1). -
Deep Learning the Hyperbolic Volume of a Knot
Physics Letters B 799 (2019) 135033 Contents lists available at ScienceDirect Physics Letters B www.elsevier.com/locate/physletb Deep learning the hyperbolic volume of a knot ∗ Vishnu Jejjala a,b, Arjun Kar b, , Onkar Parrikar b,c a Mandelstam Institute for Theoretical Physics, School of Physics, NITheP, and CoE-MaSS, University of the Witwatersrand, Johannesburg, WITS 2050, South Africa b David Rittenhouse Laboratory, University of Pennsylvania, 209 S 33rd Street, Philadelphia, PA 19104, USA c Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94305, USA a r t i c l e i n f o a b s t r a c t Article history: An important conjecture in knot theory relates the large-N, double scaling limit of the colored Jones Received 8 October 2019 polynomial J K ,N (q) of a knot K to the hyperbolic volume of the knot complement, Vol(K ). A less studied Accepted 14 October 2019 question is whether Vol(K ) can be recovered directly from the original Jones polynomial (N = 2). In this Available online 28 October 2019 report we use a deep neural network to approximate Vol(K ) from the Jones polynomial. Our network Editor: M. Cveticˇ is robust and correctly predicts the volume with 97.6% accuracy when training on 10% of the data. Keywords: This points to the existence of a more direct connection between the hyperbolic volume and the Jones Machine learning polynomial. Neural network © 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license 3 Topological field theory (http://creativecommons.org/licenses/by/4.0/). -
Stability and Triviality of the Transverse Invariant from Khovanov Homology
STABILITY AND TRIVIALITY OF THE TRANSVERSE INVARIANT FROM KHOVANOV HOMOLOGY DIANA HUBBARD AND CHRISTINE RUEY SHAN LEE Abstract. We explore properties of braids such as their fractional Dehn twist coefficients, right- veeringness, and quasipositivity, in relation to the transverse invariant from Khovanov homology defined by Plamenevskaya for their closures, which are naturally transverse links in the standard contact 3-sphere. For any 3-braid β, we show that the transverse invariant of its closure does not vanish whenever the fractional Dehn twist coefficient of β is strictly greater than one. We show that Plamenevskaya's transverse invariant is stable under adding full twists on n or fewer strands to any n-braid, and use this to detect families of braids that are not quasipositive. Motivated by the question of understanding the relationship between the smooth isotopy class of a knot and its transverse isotopy class, we also exhibit an infinite family of pretzel knots for which the transverse invariant vanishes for every transverse representative, and conclude that these knots are not quasipositive. 1. Introduction Khovanov homology is an invariant for knots and links smoothly embedded in S3 considered up to smooth isotopy. It was defined by Khovanov in [Kho00] to be a categorification of the Jones polynomial. Khovanov homology and related theories have had numerous topological applications, including a purely combinatorial proof due to Rasmussen [Ras10] of the Milnor conjecture (for other applications see for instance [Ng05] and [KM11]). In this paper we will consider Khovanov homology calculated with coefficients in Z and reduced Khovanov homology with coefficients in Z=2Z. -
On Intersection Graphs of Graphs and Hypergraphs: a Survey
Intersection Graphs of Graphs and Hypergraphs: A Survey Ranjan N. Naika aDepartment of Mathematics, Lincoln University, PA, USA [email protected] Abstract The survey is devoted to the developmental milestones on the characterizations of intersection graphs of graphs and hypergraphs. The theory of intersection graphs of graphs and hypergraphs has been a classical topic in the theory of special graphs. To conclude, at the end, we have listed some open problems posed by various authors whose work has contributed to this survey and also the new trends coming out of intersection graphs of hyeprgraphs. Keywords: Hypergraphs, Intersection graphs, Line graphs, Representative graphs, Derived graphs, Algorithms (ALG),, Forbidden induced subgraphs (FIS), Krausz partitions, Eigen values Mathematics Subject Classification : 06C62, 05C65, 05C75, 05C85, 05C69 1. Introduction We follow the terminology of Berge, C. [3] and [4]. This survey does not address intersection graphs of other types of graphs such as interval graphs etc. An introduction of intersection graphs of interval graphs etc. are available in Pal [40]. A graph or a hypergraph is a pair (V, E), where V is the vertex set and E is the edge set a family of nonempty subsets of V. Two edges of a hypergraph are l -intersecting if they share at least l common vertices. This concept was studied in [6] and [18] by Bermond, Heydemann and Sotteau. A hypergraph H is called a k-uniform hypergraph if its edges have k number of vertices. A hypergraph is linear if any two edges have at most one common vertex. A 2-uniform linear hypergraph is called a graph or a linear graph. -
ON TANGLES and MATROIDS 1. Introduction Two Binary Operations on Matroids, the Two-Sum and the Tensor Product, Were Introduced I
ON TANGLES AND MATROIDS STEPHEN HUGGETT School of Mathematics and Statistics University of Plymouth, Plymouth PL4 8AA, Devon ABSTRACT Given matroids M and N there are two operations M ⊕2 N and M ⊗ N. When M and N are the cycle matroids of planar graphs these operations have interesting interpretations on the corresponding link diagrams. In fact, given a planar graph there are two well-established methods of generating an alternating link diagram, and in each case the Tutte polynomial of the graph is related to polynomial invariant (Jones or homfly) of the link. Switching from one of these methods to the other corresponds in knot theory to tangle insertion in the link diagrams, and in combinatorics to the tensor product of the cycle matroids of the graphs. Keywords: tangles, knots, Jones polynomials, Tutte polynomials, matroids 1. Introduction Two binary operations on matroids, the two-sum and the tensor product, were introduced in [13] and [4]. In the case when the matroids are the cycle matroids of graphs these give rise to corresponding operations on graphs. Strictly speaking, however, these operations on graphs are not in general well defined, being sensitive to the Whitney twist. Consider the two-sum for a moment: when it is well defined it can be seen simply in terms of the replacement of an edge by a new subgraph: a special case of this is the operation leading to the homeomorphic graphs studied in [11]. Planar graphs define alternating link diagrams, and so the two-sum and tensor product operations are defined on these too: they correspond to insertions of tangles. -
TANGLES for KNOTS and LINKS 1. Introduction It Is
TANGLES FOR KNOTS AND LINKS ZACHARY ABEL 1. Introduction It is often useful to discuss only small \pieces" of a link or a link diagram while disregarding everything else. For example, the Reidemeister moves describe manipulations surrounding at most 3 crossings, and the skein relations for the Jones and Conway polynomials discuss modifications on one crossing at a time. Tangles may be thought of as small pieces or a local pictures of knots or links, and they provide a useful language to describe the above manipulations. But the power of tangles in knot and link theory extends far beyond simple diagrammatic convenience, and this article provides a short survey of some of these applications. 2. Tangles As Used in Knot Theory Formally, we define a tangle as follows (in this article, everything is in the PL category): Definition 1. A tangle is a pair (A; t) where A =∼ B3 is a closed 3-ball and t is a proper 1-submanifold with @t 6= ;. Note that t may be disconnected and may contain closed loops in the interior of A. We consider two tangles (A; t) and (B; u) equivalent if they are isotopic as pairs of embedded manifolds. An n-string tangle consists of exactly n arcs and 2n boundary points (and no closed loops), and the trivial n-string 2 tangle is the tangle (B ; fp1; : : : ; png) × [0; 1] consisting of n parallel, unintertwined segments. See Figure 1 for examples of tangles. Note that with an appropriate isotopy any tangle (A; t) may be transformed into an equivalent tangle so that A is the unit ball in R3, @t = A \ t lies on the great circle in the xy-plane, and the projection (x; y; z) 7! (x; y) is a regular projection for t; thus, tangle diagrams as shown in Figure 1 are justified for all tangles.