arXiv research

Study on group cocycles for volume-preserving diffeomorphisms.

Standard $S^4$ proved to be diffeomorphic to a curious homotopy sphere.

Paper proves every stable 4-sphere has a unique diffeomorphism class.

Proves constraints on groups extending Möbius transformations on spheres.

Study shows bounded cohomology vanishes for higher dimensional sphere diffeomorphisms.

We study the existence or not of harmonic diffeomorphisms between certain domains in the Euclidean 2-sphere. In particular, we show harmonic diffeomorphisms from circular domains in the complex plane onto finitely punctured spheres, with at least two punctures. This result follows from a general existence theorem for m…

New compact mean convex hypersurfaces found for positive λ.

Classifies central extensions for area-preserving diffeomorphisms and shows they are fuzzy sphere limits.

Simplified proof of Cerf's theorem on 3-sphere diffeomorphisms.

According to Pixton, there are Morse-Smale diffeomorphisms of the 3-sphere which have no energy function, that is a Lyapunov function whose critical points are all periodic points of the diffeomorphism. We introduce the concept of quasi-energy function for a Morse-Smale diffeomorphism as a Lyapunov function with the le…

Unique symplectic fillings of odd spheres' cotangent bundles proven.

For a non-orientable closed surface standardly embedded in the 4-sphere, a diffeomorphism over this surface is extendable if and only if this diffeomorphism preserves the Guillou-Marin quadratic form of this embedded surface.

New $λ$-hypersurfaces not isometric to standard spheres.

A canonical diffeomorphism is constructed for manifolds near spheres.

The paper shows how certain circle families in $S^1 imes D^3$ relate to sphere families in $S^2 imes D^2$ and induces nontrivial barbell diffeomorphisms.

A surface in the 4-sphere is trivially embedded, if it bounds a 3-dimensional handle body in the 4-sphere. For a surface trivially embedded in the 4-sphere, a diffeomorphism over this surface is extensible if and only if this preserves the Rokhlin quadratic form of this embedded surface.

The Price twist creates three 4-manifolds from a 4-sphere.

Generators of the 4-sphere's smooth mapping class group via diffeomorphisms of Montesinos twins.

The paper constructs homotopy 4-spheres using pochette surgery.

Theta graph diffeomorphism shows nontrivial mapping class of 4-sphere.

Detects exotic embeddings in 4-manifolds with boundary.

New research finds 145 infinite families of CS spheres are standard.

We prove that any diffeomorphism of the sphere S^n to itself can be decomposed into bi-Lipschitz mappings of small isometric distortion and which move points a small amount in the spherical metric.

Every smooth homotopy 4-sphere is diffeomorphic to the 4-sphere.

We construct an explicit diffeomorphism taking any fibration of a sphere by great circles into the Hopf fibration, using elementary geometry--indeed the diffeomorphism is a local (differential) invariant, algebraic in derivatives.

Gompf proposed a conjecture on Cappell-Shaneson matrices whose affirmative answer implies that all Cappell-Shaneson homotopy 4-spheres are diffeomorphic to the standard 4-sphere. We study Gompf conjecture on Cappell-Shaneson matrices using various algebraic number theoretic techniques. We find a hidden symmetry between…

We show that various classes of products of manifolds do not support transitive Anosov diffeomorphisms. Exploiting the Ruelle-Sullivan cohomology class, we prove that the product of a negatively curved manifold with a rational homology sphere does not support transitive Anosov diffeomorphisms. We extend this result to …

In this paper we extend some well-known rigidity results for conformal changes of Einstein metrics to the class of generalized quasi-Einstein (GQE) metrics, which includes gradient Ricci solitons. In order to do so, we introduce the notions of conformal diffeomorphisms and vector fields that preserve a GQE structure. W…

The paper connects diffeomorphism groups and sphere embeddings, proving a group structure.

New findings about twists in 4-sphere diffeomorphisms.

We prove that the group of area-preserving diffeomorphisms of the 2-sphere admits a non-trivial homogeneous quasimorphism to the real numbers with the following property. Its value on any diffeomorphism supported in a sufficiently small open subset of the sphere equals to the Calabi invariant of the diffeomorphism. Thi…

The paper constructs many knotted and linked objects in higher dimensions.

Gluck twisting certain knots results in standard 4-spheres.

Perelman's proof confirmed, new method uses 4D topology.

Classifies smooth manifolds homotopy equivalent to sphere products

We prove that the infinite family of homotopy 4-spheres constructed by Daniel Nash are all diffeomorphic to 4-sphere.

In this article, using combinatorial techniques of mapping class groups, we show that a Stein fillable integral homology $3$-sphere supported by an open book decomposition with page a $4$-holed sphere admits a unique Stein filling up to diffeomorphism. Furthermore, according to a property of deforming symplectic fillin…

The study examines moduli spaces of metrics with positive Ricci or non-negative sectional curvature on sphere bundles.

In terms of Turaev's shadows, we provide a sufficient condition for a compact, smooth, acyclic 4-manifold with boundary the 3-sphere to be diffeomorphic to the standard 4-ball. As a consequence, we prove that if a compact, smooth, acyclic 4-manifold with boundary the 3-sphere has shadow-complexity at most 2, then it is…

Let $X$ denote a metric Lie group diffeomorphic to $\mathbb{R}^3$ that admits an algebraic open book decomposition. In this paper we prove that if $Σ$ is an immersed surface in $X$ whose left invariant Gauss map is a diffeomorphism onto $\mathbb{S}^2$, then $Σ$ is an embedded sphere. As a consequence, we deduce that an…

We present a way of constructing and deforming diffeomorphisms of manifolds endowed with a Lie group action. This is applied to the study of exotic diffeomorphisms and involutions of spheres and to the equivariant homotopy of Lie groups.

Derivative map for disk diffeomorphisms induces nontrivial homotopy groups.

A closed manifold is called a biquotient if it is diffeomorphic to K\G/H for some compact Lie group G with closed subgroups K and H such that K acts freely on G/H. Biquotients are a major source of examples of Riemannian manifolds with nonnegative sectional curvature. We prove several classification results for biquoti…

In this paper we discuss the relationship between groups of diffeomorphisms of spheres and balls. We survey results of a topological nature and then address the relationship as abstract (discrete) groups. We prove that the identity component Diff_0(S^{2n-1}) of the group of smooth diffeomorphisms of S^{2n+1} admits no …

Heegaard diagrams for 5-manifolds help in understanding their structure.

We consider two pairs: the standard unknotted $n$-sphere in $S^{n+2}$, and the product of two $p$-spheres trivially embedded in $S^{2p+2}$, and study orientation preserving diffeomorphisms of these pairs. Pseudo-isotopy classes of such diffeomorphisms form subgroups of the mapping class groups of $S^n$ and $S^p\times S…

Study pochette surgery on 4-manifolds, focusing on 4-spheres.

We show that any effective isometric torus action of maximal rank on a compact Riemannian manifold with positive (sectional) curvature and maximal symmetry rank, that is, on a positively curved sphere, lens space, complex or real projective space, is equivariantaly diffeomorphic to a linear action. We show that a compa…