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36 results for achiral

Study on automorphisms of K3 and Enriques surfaces, proving entropy gaps and achirality.

problem Entropy norms and achirality of automorphisms on K3 and Enriques surfaces.
method Proves gap theorems for entropy norms and studies achirality in terms of genus-one fibrations.
result Entropy gaps and achirality results for automorphisms of K3 and Enriques surfaces.

We give constructions to realize an odd number, which is representable as sum of two squares, as determinant of an achiral knot, thus proving that these are exactly the numbers occurring as such determinants. Later we study which numbers occur as determinants of prime alternating achiral knots, and obtain a complete re…

2000-03-27abs ↗pdf ↗

Study embedding of achiral Lefschetz fibrations in 6D manifolds.

problem Embedding achiral Lefschetz fibrations in 6D manifolds.
method Analyzing Lefschetz fibrations bounding open books and embedding them in 6D manifolds.
result Every achiral Lefschetz fibration with hyperelliptic monodromy admits LF embedding in D6=D2imesD4D^6 = D^2 imes D^4.

This article is devoted to the study of prime alternating +achiral knots. In the case of arborescent knots, we prove in +AAA Visibility Theorem 5.1, that the symmetry is visible on a certain projection (not necessarily minimal) and that it is realised by a homeomorphism of order 4. In the general case (arborescent or n…

2015-03-06abs ↗pdf ↗

We give a counterexample to the Kawauchi conjecture on the Conway polynomial of achiral knots which asserts that the Conway polynomial C(z)C(z) of an achiral knot satisfies the splitting property C(z)=F(z)F(z)C(z)=F(z)F(-z) for a polynomial F(z)F(z) with integer coefficients. We show that the Bonahon-Siebenmann decomposition of an ac…

2011-06-28abs ↗pdf ↗

We show that any 4-manifold, after surgery on a curve, admits an achiral Lefschetz fibration. In particular, we show that the connected sum of any simply connected 4-manifold with a 2-sphere bundle over the 2-sphere will admit an achiral Lefschetz fibration. We also show these surgered manifolds admit near-symplectic s…

2005-09-30abs ↗pdf ↗

We will develop various methods, some are of geometric nature and some are of algebraic nature, to detect the various achiralities of knots and links in S3S^3. For example, we show that the twisted Whitehead double of a knot is achiral if and only if the double is the unknot or the figure eight knot, and we show that a…

1999-05-25abs ↗pdf ↗

In this paper we are interested in symmetries of alternating knots, more precisely in those related to achirality. We call the following statement Tait's Conjecture on alternating -achiral knots: Let K be an alternating -achiral knot. Then there exists a minimal projection Π of K in S^2 \subset S^3 and an involution φ:…

2011-03-16abs ↗pdf ↗

This note presents the handlebody argument for modifying achiral Lefschetz singularities into broken Lefschetz fibrations, yielding a handlebody proof of the existence of broken Lefschetz fibrations on arbitrary closed smooth oriented 4-manifolds based on the earlier work of Gay and Kirby. Appeared in Geometry and Topo…

2010-09-06abs ↗pdf ↗

We classify all knot diagrams of genus two and three, and give applications to positive, alternating and homogeneous knots, including a classification of achiral genus 2 alternating knots, slice or achiral 2-almost positive knots, a proof of the 3- and 4-move conjectures, and the calculation of the maximal hyperbolic v…

2003-03-02abs ↗pdf ↗

An ordered and oriented 2-component link L in the 3-sphere is said to be achiral if it is ambient isotopic to its mirror image ignoring the orientation and ordering of the components. Kirk-Livingston showed that if L is achiral then the linking number of L is not congruent to 2 modulo 4. In this paper we study orientat…

2007-08-01abs ↗pdf ↗

Solenoids are ``inverse limits'' of the circle, and the classical knot theory is the theory of tame embeddings of the circle into the 3-space. We give some general study, including certain classification results, of tame embeddings of solenoids into the 3-space as the ``inverse limits'' of the tame embeddings of the ci…

2006-11-29abs ↗pdf ↗

The paper extends trisection construction for Lefschetz fibrations with (n)(-n)-sections.

problem Constructing trisections for 4-manifolds with specific Lefschetz fibrations.
method Explicit construction of trisections using monodromies of Lefschetz fibrations.
result Trisections for various 4-manifolds constructed from Lefschetz fibrations.

According to our previous results, the conjugacy class of the involution induced by the complex conjugation in the homology of a real non-singular cubic fourfold determines the fourfold up to projective equivalence and deformation. Here, we show how to eliminate the projective equivalence and to obtain a pure deformati…

2008-04-30abs ↗pdf ↗

Log-symplectic structures are Poisson structures ππ on X2nX^{2n} for which nπ\bigwedge^n π vanishes transversally. By viewing them as symplectic forms in a Lie algebroid, the bb-tangent bundle, we use symplectic techniques to obtain existence results for log-symplectic structures on total spaces of fibration-like maps…

2016-06-01abs ↗pdf ↗

The main result of this paper is that for every closed, connected, orientable, irreducible 3-manifold MM, there is an integer nM n_M such that any abstract graph with no automorphism of order 2 which has a 3-connected minor whose genus is more than nMn_M has no achiral embedding in MM. By contrast, the paper also pro…

2014-06-12abs ↗pdf ↗

We show how to construct broken, achiral Lefschetz fibrations on arbitrary smooth, closed, oriented 4-manifolds. These are generalizations of Lefschetz fibrations over the 2-sphere, where we allow Lefschetz singularities with the non-standard orientation as well as circles of singularities corresponding to round 1-hand…

2007-01-03abs ↗pdf ↗

We employ a certain labeled finite graph, called a chart, in a closed oriented surface for describing the monodromy of a(n achiral) Lefschetz fibration over the surface. Applying charts and their moves with respect to Wajnryb's presentation of mapping class groups, we first generalize a signature formula for Lefschetz …

2014-03-31abs ↗pdf ↗

Using the Fiedler-Polyak-Viro Gauss diagram formulas we study the Vassiliev invariants of degree 2 and 3 on almost positive knots. As a consequence we show that the number of almost positive knots of given genus or unknotting number grows polynomially in the crossing number, and also recover and extend, inter alia to t…

1998-03-17abs ↗pdf ↗

We describe rational knots with any of the possible combinations of the properties (a)chirality, (non-)positivity, (non-)fiberedness, and unknotting number one (or higher), and determine exactly their number for a given number of crossings in terms of their generating functions. We show in particular how Fibonacci numb…

2002-10-11abs ↗pdf ↗

Singular fibrations over surfaces generalize Lefschetz fibrations and have new construction methods.

problem Understanding and constructing singular fibrations over surfaces.
method Explains how to construct examples of singular fibrations with a single singularity and outlines previous results.
result Closed orientable 4-manifolds with large first Betti number and vanishing second Betti number do not admit singular fibrations.

In this paper, we use `generalized Seifert surfaces' to extend the Levine-Tristram signature to colored links in S^3. This yields an integral valued function on the m-dimensional torus, where m is the number of colors of the link. The case m=1 corresponds to the Levine-Tristram signature. We show that many remarkable p…

2005-05-10abs ↗pdf ↗

The paper explores conditions for sections in Lefschetz fibrations and bundles over 2-complexes.

problem Conditions for sections in Lefschetz fibrations and bundles over 2-complexes.
method Algebraic criteria and topological conditions.
result Complete algebraic criterion for sections in Lefschetz fibrations over the disk.

New invariant defined for Weinstein domains, related to Kirby-Thompson's invariant.

problem Defining a symplectic invariant for Weinstein domains.
method Contact cut graph, Lefschetz fibrations, multisections with divides.
result Definition of Weinstein L\mathcal{L}-invariant and its relation to Kirby-Thompson's invariant.

Motivated by the programmes initiated by Taubes and Perutz, we study the geometry of near-symplectic 4-manifolds, i.e., manifolds equipped with a closed 2-form which is symplectic outside a union of embedded 1-dimensional submanifolds, and broken Lefschetz fibrations on them. We present a set of four moves which allow …

2007-12-13abs ↗pdf ↗

We continue the study of the genus of knot diagrams, deriving a new description of generators using Hirasawa's algorithm. This description leads to good estimates on the maximal number of crossings of generators and allows us to complete their classification for knots of genus 4. As applications of the genus 4 classifi…

2011-01-18abs ↗pdf ↗

In this thesis we study geometric structures from Poisson and generalized complex geometry with mild singular behavior using Lie algebroids. The process of lifting such structures to their Lie algebroid version makes them less singular, as their singular behavior is incorporated in the anchor of the Lie algebroid. We d…

2017-12-27abs ↗pdf ↗

The paper studies π1π_1-injective bounding of manifolds and its applications.

problem Understanding π1π_1-injective bounding of manifolds and its implications.
method Proves conditions for π1π_1-injective bounding and applies to 3- and 4-manifolds.
result Closed 3-manifolds π1π_1-injectively bound 4-manifolds with residually finite π1π_1.