New smoothing techniques for topological surfaces in 4-manifolds.
problem Topological isotopy of surfaces in smooth 4-manifolds.
method Combining Quinn's smoothing theory with Gabai's light bulb theorem and other developments.
result Proves topological = smooth results for certain disks and spheres.
Improved proofs for topological and smooth pseudo-isotopies of simply connected 4-manifolds.
problem Proving topological and smooth pseudo-isotopies of simply connected 4-manifolds.
method Provided different arguments that bypass the replacement criterion, thus completing Quinn's proofs.
result Corrected and completed Quinn's proofs of both topological and stable smooth pseudo-isotopy theorems.
New method constructs Stein surfaces using topological isotopy.
problem Creating Stein surfaces in complex surfaces.
method Combining Freedman's topology with Eliashberg's holomorphic theory.
result Every tame 2-complex can be isotoped to a Stein surface.
Smooth isotopy on cube saves energy with extra dimensions.
problem Constructing an isotopy with infinite kinetic energy.
method Explicit construction of isotopy on [0,1]n. result Existence of isotopy with infinite kinetic energy.
Classifies curves up to symplectic isotopy.
problem Classifying rational cuspidal curves up to symplectic isotopy.
method Topological tools, pseudoholomorphic techniques, and birational transformations.
result Classifies rational cuspidal curves of degrees 6 and 7 up to symplectic isotopy.
Finite type invariants separate PL links in 3D space.
problem If two PL links are isotopic, are they PL isotopic?
method Proved PL isotopic links are indistinguishable by finite type invariants.
result Finite type invariants separate PL links in 3D space if and only if certain conjectures hold.
In this paper we define and study flexible links and flexible isotopy in projective space. Flexible links are meant to capture the topological properties of real algebraic links. We classify all flexible links up to flexible isotopy using Ekholms interpretation of Viros encomplexed writhe.
We prove that a topological contact isotopy uniquely defines a topological contact Hamiltonian. Combined with previous results from [MS11], this generalizes the classical one-to-one correspondence between smooth contact isotopies and their generating smooth contact Hamiltonians and conformal factors to the group of top…
New unknots with geometric constraints exist, proving a long-standing conjecture.
problem Existence of distinct isotopy classes of physical unknots with geometric constraints.
method Parametrised thickness and geometric thresholds to fragment isotopy classes.
result Existence of gordian unknots with prescribed geometric constraints.
New obstructions show some 4-manifold homeomorphisms are pseudo-isotopic but not isotopic.
problem Tackling the difference between pseudo-isotopy and isotopy for 4-manifolds.
method Defining and showing realizable obstructions in Whitehead groups.
result Found homeomorphisms that are pseudo-isotopic but not isotopic.
Example shows smooth vs topological isotopy in a 4-manifold.
problem Smooth vs topological isotopy in a specific 4-manifold.
method Constructing specific embeddings and isotopies.
result Found a smooth embedding not isotopic to a topological one.
Study on topological pseudo-isotopies of 4-manifolds, proving some cases and finding counterexamples.
problem Determining when a topologically pseudo-isotopic diffeomorphism is also smoothly pseudo-isotopic.
method Analyzing the fundamental group of 4-manifolds and constructing counterexamples.
result Some fundamental groups guarantee a positive answer, while others can have negative outcomes.
New gauge theory invariant detects non-smooth isotopy of P2-knots.
problem Detecting non-smooth isotopy of P2-knots. method Real Seiberg-Witten theory to construct a gauge theoretic invariant.
result Found a family of P2-knots that are topologically isotopic but not smoothly isotopic. Various standard texts on differential topology maintain that the level-preserving map defined by the track of an isotopy of embeddings is itself an embedding. This note describes a simple counterexample to this assertion.
Smoothly isotopic surfaces in a 4-manifold are stable isotopic if trivial in the 2-homology.
problem Investigating whether topologically isotopic surfaces are smoothly isotopic in stabilised 4-manifolds.
method Analyzing the triviality of surfaces in the 2-homology of the ambient 4-manifold and constructing stabilisations.
result The result holds for surfaces trivial in the 2-homology of the 4-manifold and for certain fundamental groups.
Introduces a Cost function to measure Legendrian knot obstructions.
problem Measuring obstructions for Legendrian knot isotopies.
method Introduces a non-negative integer-valued Cost function.
result Cost function induces a metric on topologically isotopic Legendrian knots.
Paper defines and analyzes mathematical equivalence of periodic tangles.
problem Understanding the equivalence of periodic tangles.
method Established mathematical framework, characterized isotopies, generalized results.
result Characterization of DP tangle equivalence based on motifs.
This paper studies isotopies of periodic tangles in 3-manifolds using finite covers.
problem Understanding equivalence relations of periodic tangles in 3-manifolds.
method Employing techniques from 3-manifold topology to study complements of links.
result Isotopies between different finite covers of isotopic links are preserved.
Fractional Dehn twists give a measure of the difference between the relative isotopy class of a homeomorphism of a bordered surface and the Thurston representative of its free isotopy class. We show how to estimate and compute these invariants. We discuss the the relationship of our work to stabilization problems in cl…
The space of n-sided polygons embedded in three-space consists of a smooth manifold in which points correspond to piecewise linear or ``geometric'' knots, while paths correspond to isotopies which preserve the geometric structure of these knots. The topology of these spaces for the case n = 6 and n = 7 is described. In…
Study of Lagrangian submanifolds with Riemannian bounds and their metric properties.
problem Understanding the geometry and topology of Lagrangian submanifolds with Riemannian constraints.
method Investigation of metric properties and symplectic structures on spaces of Lagrangian submanifolds with uniform Riemannian bounds.
result There are at most countably many Hamiltonian isotopy classes of exact Lagrangian submanifolds in a Liouville manifold.
New link found that can't be smoothly deformed.
problem Existence of non-isotopic links.
method Constructed a specific link in 3-space.
result Uncountably many I-equivalence classes of links.
We discuss the properties of a certain type of Dehn surgery along a Lagrangian torus in a symplectic 4-manifold, known as Luttinger's surgery, and use this construction to provide a purely topological interpretation of a non-isotopy result for symplectic plane curves with cusp and node singularities due to Moishezon.
The paper defines a stratification for Lie groupoids in a tame topology context.
problem Presenting a tame topology counterpart to canonical stratification of Lie groupoids.
method Using Shiota's isotopy lemma and approximation theorem, the paper defines a canonical Whitney stratification of definable Lie groupoids into invariant strata.
result A canonical Whitney stratification of the Lie groupoid into definable strata invariant under the groupoid action.
Physical knots and links are one-dimensional submanifolds of R^3 with fixed length and thickness. We show that isotopy classes in this category can differ from those of classical knot and link theory. In particular we exhibit a Gordian Split Link, a two component link that is split in the classical theory but cannot be…
New obstruction found for embedding Riemannian manifolds into Euclidean spaces.
problem Embedding Riemannian manifolds into Euclidean spaces with specific conditions.
method Motivated by incompressible Euler equations, a dynamical-topological obstruction is derived.
result Nontrivial first real homology and trivial center of fundamental group imply embedding violation.
We generalize the "hamiltonian topology" on hamiltonian isotopies to an intrinsic "symplectic topology" on the space of symplectic isotopies. We use it to define the group SSympeo(M,ω) of strong symplectic homeomorphisms, which generalizes the group Hameo(M,ω) of hamiltonian homeomorphisms introduced by Oh and Mull…
We give an overview of various recent results concerning the topology of symplectic 4-manifolds and singular plane curves, using branched covers and isotopy problems as a unifying theme. While this paper does not contain any new results, we hope that it can serve as an introduction to the subject, and will stimulate in…
Solves a problem about deforming symplectic forms on a Klein bottle.
problem Deforming symplectic forms on a nonorientable Lagrangian surface.
method Analyzes a specific Lagrangian Klein bottle in a symplectic 4-manifold.
result Shows how far symplectic forms can be deformed before isotopy classes contain no Lagrangians.
Example of non-smooth isotopy using K3 surfaces.
problem Non-smooth isotopy examples in 4-manifolds.
method Dehn twist along a 3-sphere in K3 surfaces' connected sum.
result First example of self-diffeomorphisms isotopic to identity but not smoothly.
The paper studies elliptic surfaces and proves unique fibered structures.
problem Understanding the structure of elliptic fibrations and their mapping class groups.
method Analyzes smooth 4-manifolds and uses Néron-Lang Theorem. result Proves the uniqueness of fibered structures in elliptic fibrations.
We define a suitably tame class of singular symplectic curves in 4-manifolds, namely those whose singularities are modeled on complex curve singularities. We study the corresponding symplectic isotopy problem, with a focus on rational curves with irreducible singularities (rational cuspidal curves) in the complex proje…
In this note, we discuss the mean curvature flow of graphs of maps between Riemannian manifolds. Special emphasis will be placed on estimates of the flow as a non-linear parabolic system of differential equations. Several global existence theorems and applications to isotopy problems in geometry and topology will be pr…
Quantum model for knotted graphs from knot theory.
problem Constructing an isotopy invariant polynomial for knotted bipartite ribbon graphs.
method Applying quantum topology to construct an isotopy invariant polynomial.
result Computed the expected number of loops in the double dimer model.
Study of disks in complex projective space with specific fundamental groups.
problem Locally flat disks with boundary a fixed knot in (CP2)∘ with Z-fundamental group. method Topological isotopy, crossing changes, and algebraic invariants.
result Existence and classification of Z-disks in (CP2)∘. The paper defines a condition for the finiteness of mapping class groups of Heegaard splittings.
problem Conditions for the finiteness of mapping class groups of Heegaard splittings.
method Use of the thick isotopy lemma to establish conditions for finiteness.
result Heegaard splittings with topologically minimal disk complex and finitely generated homotopy group have finitely generated mapping class groups.
Defines Lorentzian distance on contactomorphisms, proving continuity and finite conditions.
problem Continuous distance function on contactomorphisms with finite intervals.
method Defining and analyzing Lorentzian distance functions, proving continuity and finite intervals.
result Distance function is continuous and finite if and only if contactomorphisms are orderable.
Geometric aspects of the filtration on classical links by k-quasi-isotopy are discussed, including the effect of Whitehead doubling, relations with Smythe's n-splitting and Kobayashi's k-contractibility. One observation is: ω-quasi-isotopy is equivalent to PL isotopy for links in a homotopy 3-sphere (resp. contractible…
For Gamma a finite, connected metric graph, we consider the space of configurations of n points in Gamma with a restraint parameter r dictating the minimum distance allowed between each pair of points. These restricted configuration spaces come up naturally in topological robotics. In this paper, we study the homotopy,…
New method shows nonorientable surfaces in 4D are topologically unknotted.
problem Tackles isotopy classes of nonorientable surfaces in D4. method Calculations implemented in Sage to show ambient isotopy.
result Closed, nonorientable surfaces in S4 are topologically unknotted. We prove a neighbourhood theorem for arbitrary knots in contact 3-manifolds. As an application we show that two topologically isotopic Legendrian knots in a contact 3-manifold become Legendrian isotopic after suitable stabilisations.
This is an introductory text on the more topological aspects of contact geometry, written for the Handbook of Differential Geometry vol. 2. After discussing (and proving) some of the fundamental results of contact topology (neighbourhood theorems, isotopy extension theorems, approximation theorems), I move on to a deta…
For a fixed regular cone in Euclidean space with small entropy we show that all smooth self-expanding solutions of the mean curvature flow that are asymptotic to the cone are in the same isotopy class.
Study shows how to create 2-links with any group in 4-manifolds.
problem Creating 2-links with any given group in 4-manifolds.
method Constructing simply connected 4-manifolds containing 2-links with specific properties.
result 2-links can have any group as their 2-link group.
New examples show limits of physical link isotopies.
problem Limits of physical link isotopies in thick and thickly embedded links.
method Construction of specific examples of thick and thickly embedded links.
result Explicit examples of links that cannot be split through thick homotopies.
New algebraic structure for 2-string links and long knots.
problem Understanding the space of 2-string links and long knots.
method Realized L as a free algebra over a colored operad SCL. result Expressed the isotopy class of a 2-string link in terms of its prime factors.
The paper studies co-Hamiltonian diffeomorphisms on compact cosymplectic manifolds.
problem Fix-point theory and co-Hamiltonian diffeomorphisms on compact cosymplectic manifolds.
method Fix-point theory, Arnold's conjecture, co-Hofer norms, topologies, approximations lemmas.
result Minimum number of fix points for co-Hamiltonian diffeomorphisms is at least 1.
The paper gives topological as well as rigid isotopy classification of smooth irreducible algebraic curves in the real projective 3-space for the case when the degree of the curve is at most six and its genus is at most one.