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We investigate the $C^0$-topology of the group of symplectic diffeomorphisms of positive symplectic rational surfaces. For all but a few exceptions, we prove that the group of Hamiltonian diffeomorphisms forms a connected component in the…

Symplectic Geometry · Mathematics 2025-08-29 Marcelo Atallah , Cheuk Yu Mak , Weiwei Wu

The celebrated Morlet-Burghelea-Lashof-Kirby-Siebenmann smoothing theory theorem states that the group $\mathrm{Diff}_\partial(D^n)$ of diffeomorphisms of a disc $D^n$ relative to the boundary is equivalent to…

Geometric Topology · Mathematics 2026-03-06 Paolo Salvatore , Victor Turchin

We study the infinite generation in the homotopy groups of the group of diffeomorphisms of $S^1 \times D^{2n-1}$, for $2n \geq 6$, in a range of degrees up to $n-2$. Our analysis relies on understanding the homotopy fibre of a linearisation…

Algebraic Topology · Mathematics 2024-07-24 Mauricio Bustamante , Oscar Randal-Williams

We study proper rational maps from the unit disk to balls in higher dimensions. After gathering some known results, we study the moduli space of unitary equivalence classes of polynomial proper maps from the disk to a ball, and we establish…

Complex Variables · Mathematics 2016-08-10 John P. D'Angelo , Zhenghui Huo , Ming Xiao

In this paper we give a full diffeomorphism characterization of compact simply connected cohomogeneity one manifolds in dimension six.

Differential Geometry · Mathematics 2009-07-16 Corey A. Hoelscher

We determine all the normal subgroups of the group of C^r diffeomorphisms of R^n, r = 1,2,...,infinity, except when r=n+1 or n=4, and also of the group of homeomorphisms of R^n (r=0). We also study the group A_0 of diffeomorphisms of an…

Geometric Topology · Mathematics 2012-04-12 Paul A. Schweitzer S. J.

Differential calculus on Euclidean spaces has many generalisations. In particular, on a set $X$, a diffeological structure is given by maps from open subsets of Euclidean spaces to $X$, a differential structure is given by maps from $X$ to…

Differential Geometry · Mathematics 2023-05-05 Augustin Batubenge , Yael Karshon , Jordan Watts

We consider the groups $\operatorname{Diff}_{\mathcal B}(\mathbb R^n)$, $\operatorname{Diff}_{H^\infty}(\mathbb R^n)$, and $\operatorname{Diff}_{\mathcal S}(\mathbb R^n)$ of smooth diffeomorphisms on $\mathbb R^n$ which differ from the…

Functional Analysis · Mathematics 2014-10-07 Peter W. Michor , David Mumford

We study families of diffeomorphisms detected by trivalent graphs via the Kontsevich classes. We specify some recent results and constructions of the second named author to show that those non-trivial elements in homotopy groups…

Geometric Topology · Mathematics 2023-01-19 Boris Botvinnik , Tadayuki Watanabe

The main purpose of this paper is to propose a scheme of a proof of the nonsimpleness of the group $Homeo^\Omega(D^2,\partial D^2)$ of area preserving homeomorphisms of the 2-disc $D^2$. We first establish the existence of Alexander isotopy…

Symplectic Geometry · Mathematics 2016-06-23 Yong-Geun Oh

We prove that a pseudoholomorphic diffeomorphism between two almost complex manifolds with boundaries satisfying some pseudoconvexity type condition cannot map a pseudoholomorphic disc in the boundary to a single point. This can be viewed…

Complex Variables · Mathematics 2007-05-23 Klas Diederich , Alexandre Sukhov

We discuss the dynamics of smooth diffeomorphisms of the disc with vanishing topological entropy which satisfy the mild dissipation property introduced in [CP]. In particular it contains the H\'enon maps with Jacobian up to 1/4. We prove…

Dynamical Systems · Mathematics 2023-02-14 Sylvain Crovisier , Enrique Pujals , Charles Tresser

We prove that every $C^\infty$-smooth, area preserving diffeomorphism of the closed 2-disk having not more than one periodic point is the uniform limit of periodic $C^\infty$-smooth diffeomorphisms. In particular every smooth irrational…

Dynamical Systems · Mathematics 2012-04-23 Barney Bramham

Spaces of holomorphic maps from the Riemann sphere to various complex manifolds (holomorphic curves ) have played an important role in several area of mathematics. In a seminal paper G. Segal investigated the homotopy type of holomorphic…

Algebraic Topology · Mathematics 2017-07-26 Andrzej Kozlowski , Kohhei Yamaguchi

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…

Geometric Topology · Mathematics 2013-04-11 Kathryn Mann

We show that discrete and classical homotopy theories are equivalent after localizing at n-equivalences for any non-negative integer n. By constructing an explicit homotopy inverse to the graph nerve functor associating an n-fibrant cubical…

Algebraic Topology · Mathematics 2026-02-24 Daniel Carranza , Chris Kapulkin

Diffeological spaces are generalizations of smooth manifolds which include singular spaces and function spaces. For each diffeological space, Iglesias-Zemmour introduced a natural topology called the $D$-topology. However, the $D$-topology…

Differential Geometry · Mathematics 2015-09-17 J. Daniel Christensen , Gord Sinnamon , Enxin Wu

The thesis deals with recognizing diffeomorphisms from fractal properties of discrete orbits, generated by iterations of such diffeomorphisms. The notion of fractal properties of a set refers to the box dimension, the Minkowski content and…

Dynamical Systems · Mathematics 2015-05-12 Maja Resman

This note serves to record examples of diffeomorphisms of closed smooth $4$-manifolds $X$ that are homotopic but not pseudoisotopic to the identity, and to explain why there are no such examples when $X$ is orientable and its fundamental…

Geometric Topology · Mathematics 2024-09-19 Manuel Krannich , Alexander Kupers

Consider a connected manifold of dimension at least two and the group of compactly supported diffeomorphisms that are compactly supported isotopic to the identity. This group acts $n$-transitive: Any tuple of $n$ points can be moved to any…

Geometric Topology · Mathematics 2021-02-15 Federica Pasquotto , Thomas O. Rot