The diameter of the symplectomorphism group is infinite.
The diffeomorphism group of a Lie foliation
We describe explicitly the group of transverse diffeomorphisms of several types of minimal linear foliations on the torus , . We show in particular that non-quadratic foliations are rigid, in the sense that their only transverse diffeomorphisms are and translations. The description derives from a general formula valid for the group of transverse diffeomorphisms of any minimal Lie foliation on a compact manifold. Our results generalize those of P. Donato and P. Iglesias for , P. Iglesias and...
The Euler characteristic of vector fields on Banach manifolds and the problem of Plateau
The Frobenius theorem on -dimensional quantum hyperplane.
The Frölicher-Nijenhuis bracket on some functional spaces
Two fiber bundles E₁ and E₂ over the same base space M yield the fibered set ℱ(E₁,E₂) → M, whose fibers are defined as , for each x ∈ M. This fibered set can be regarded as a smooth space in the sense of Frölicher and we construct its tangent prolongation. Then we extend the Frölicher-Nijenhuis bracket to projectable tangent valued forms on ℱ(E₁,E₂). These forms turn out to be a kind of differential operators. In particular, we consider a general connection on ℱ(E₁,E₂) and study the associated...
The garden of quantum spheres
A list of known quantum spheres of dimension one, two and three is presented.
The geometry of Kato Grassmannians
We discuss Fredholm pairs of subspaces and associated Grassmannians in a Hilbert space. Relations between several existing definitions of Fredholm pairs are established as well as some basic geometric properties of the Kato Grassmannian. It is also shown that the so-called restricted Grassmannian can be endowed with a natural Fredholm structure making it into a Fredholm Hilbert manifold.
The ..-invariant of hyperbolic 3-manifolds.
The Lie group of real analytic diffeomorphisms is not real analytic
We construct an infinite-dimensional real analytic manifold structure on the space of real analytic mappings from a compact manifold to a locally convex manifold. Here a map is defined to be real analytic if it extends to a holomorphic map on some neighbourhood of the complexification of its domain. As is well known, the construction turns the group of real analytic diffeomorphisms into a smooth locally convex Lie group. We prove that this group is regular in the sense of Milnor. ...
The Local Index Formula in Noncommutative Geometry.
The Morse-Sard-Brown Theorem for Functionals on Bounded Fréchet-Finsler Manifolds
In this paper we study Lipschitz-Fredholm vector fields on bounded Fréchet-Finsler manifolds. In this context we generalize the Morse-Sard-Brown theorem, asserting that if is a connected smooth bounded Fréchet-Finsler manifold endowed with a connection and if is a smooth Lipschitz-Fredholm vector field on with respect to which satisfies condition (WCV), then, for any smooth functional on which is associated to , the set of the critical values of is of first category in . Therefore,...
The noncommutative Dirac equation for some wave functions.
The quantum spheres and their embedding into quantum Minkowski space-time.
The rectifiable distance in the unitary Fredholm group
Let = u: u unitary and u-1 compact stand for the unitary Fredholm group. We prove the following convexity result. Denote by the rectifiable distance induced by the Finsler metric given by the operator norm in . If and the geodesic β joining u₀ and u₁ in satisfy , then the map is convex for s ∈ [0,1]. In particular, the convexity radius of the geodesic balls in is π/4. The same convexity property holds in the p-Schatten unitary groups = u: u unitary and u-1 in the p-Schatten class...
The relation between the associate almost complex structure to and -Cartan connections.
The scattering problem for a noncommutative nonlinear Schrödinger equation.
The Schwarz Lemma and the Hadamard Three-Spheres Theorem in Hilbert Spaces.
Théorie du degré dans certains espaces de Fréchet d'après R. S. Hamilton
Topological groups and convex sets homeomorphic to non-separable Hilbert spaces
Let X be a topological group or a convex set in a linear metric space. We prove that X is homeomorphic to (a manifold modeled on) an infinite-dimensional Hilbert space if and only if X is a completely metrizable absolute (neighborhood) retract with ω-LFAP, the countable locally finite approximation property. The latter means that for any open cover of X there is a sequence of maps (f n: X → X)nεgw such that each f n is -near to the identity map of X and the family f n(X)n∈ω is locally finite...
Twisted spectral triples and covariant differential calculi
Connes and Moscovici recently studied "twisted" spectral triples (A,H,D) in which the commutators [D,a] are replaced by D∘a - σ(a)∘D, where σ is a second representation of A on H. The aim of this note is to point out that this yields representations of arbitrary covariant differential calculi over Hopf algebras in the sense of Woronowicz. For compact quantum groups, H can be completed to a Hilbert space and the calculus is given by bounded operators. At the end, we discuss an explicit example of...