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A remark on almost umbilical hypersurfaces

Julien Roth (2013)

Archivum Mathematicum

In this article, we prove new stability results for almost-Einstein hypersurfaces of the Euclidean space, based on previous eigenvalue pinching results. Then, we deduce some comparable results for almost umbilical hypersurfaces.

A remark on semi-∇-flat functions

Wojciech Kozłowski (2006)

Annales Polonici Mathematici

We give a pointwise characterization of semi-∇-flat functions on an affine manifold (M,∇).

A representation of the coalgebra of derivations for smooth spaces

Fischer, Gerald (1999)

Proceedings of the 18th Winter School "Geometry and Physics"

Let K be a field. The generalized Leibniz rule for higher derivations suggests the definition of a coalgebra 𝒟 K k for any positive integer k . This is spanned over K by d 0 , ... , d k , and has comultiplication Δ and counit ε defined by Δ ( d i ) = j = 0 i d j d i - j and ε ( d i ) = δ 0 , i (Kronecker’s delta) for any i . This note presents a representation of the coalgebra 𝒟 K k by using smooth spaces and a procedure of microlocalization. The author gives an interpretation of this result following the principles of the quantum theory of geometric spaces.

A Riemann-Roch-Hirzebruch formula for traces of differential operators

Markus Engeli, Giovanni Felder (2008)

Annales scientifiques de l'École Normale Supérieure

Let D be a holomorphic differential operator acting on sections of a holomorphic vector bundle on an n -dimensional compact complex manifold. We prove a formula, conjectured by Feigin and Shoikhet, giving the Lefschetz number of D as the integral over the manifold of a differential form. The class of this differential form is obtained via formal differential geometry from the canonical generator of the Hochschild cohomology H H 2 n ( 𝒟 n , 𝒟 n * ) of the algebra of differential operators on a formal neighbourhood of a...

A rigidity theorem for Riemann's minimal surfaces

Pascal Romon (1993)

Annales de l'institut Fourier

We describe first the analytic structure of Riemann’s examples of singly-periodic minimal surfaces; we also characterize them as extensions of minimal annuli bounded by parallel straight lines between parallel planes. We then prove their uniqueness as solutions of the perturbed problem of a punctured annulus, and we present standard methods for determining finite total curvature periodic minimal surfaces and solving the period problems.

A rough curvature-dimension condition for metric measure spaces

Anca-Iuliana Bonciocat (2014)

Open Mathematics

We introduce and study a rough (approximate) curvature-dimension condition for metric measure spaces, applicable especially in the framework of discrete spaces and graphs. This condition extends the one introduced by Karl-Theodor Sturm, in his 2006 article On the geometry of metric measure spaces II, to a larger class of (possibly non-geodesic) metric measure spaces. The rough curvature-dimension condition is stable under an appropriate notion of convergence, and stable under discretizations as...

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