Concept

Caractéristique d'Euler

Publications associées (63)

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The norm of the Euler class

Nicolas Monod

We prove that the norm of the Euler class

\mathcal{E}

for flat vector bundles is

2^{-n}

(in even dimension

n

, since it vanishes in odd dimension). This shows that the Sullivan-Smillie bound considered by Gromov and Ivanov-Turaev is sharp. We construc ...

Springer Verlag2012

Prym varieties of spectral covers

Tamás Hausel

Given a possibly reducible and non-reduced spectral cover pi: X -> C over a smooth projective complex curve C we determine the group of connected components of the Prym variety Prym(X/C). As an immediate application we show that the finite group of n-torsi ...

Geometry & Topology Publications2012

Diameter of Polyhedra: Limits of Abstraction

Friedrich Eisenbrand, Thomas Rothvoss, Nicolai Hähnle

We investigate the diameter of a natural abstraction of the 1-skeleton of polyhedra. Even if this abstraction is more general than other abstractions previously studied in the literature, known upper bounds on the diameter of polyhedra continue to hold her ...

2010

Chow-Witt groups and Grothendieck-Witt groups of regular schemes

Jean Fasel

Let A be a noetherian commutative Z[1/2]-algebra of Krull dimension d and let P be a projective A-module of rank d. We use derived Grothendieck-Witt groups and Euler classes to detect some obstructions for P to split off a free factor of rank one. If d

2009

Ordered and Oriented Supramolecular n/p-Heterojunction Surface Architectures: Completion of the Primary Color Collection

Natalie Renuka Banerji, Daniel Emery, Stefan Matile, Michal Borkovec, Plinio Maroni, Eric Vauthey

In this study, we describe synthesis, characterization, and zipper assembly of yellow p-oligophenyl naphthalenediimide (POP-NDI) donor−acceptor hybrids. Moreover, we disclose, for the first time, results from the functional comparison of zipper and layer-b ...

2009

On Singular Poisson Sternberg Spaces

We obtain a theory of stratified Sternberg spaces thereby extending the theory of cotangent bundle reduction for free actions to the singular case where the action on the base manifold consists of only one orbit type. We find that the symplectic reduced sp ...

2009

Diameter of Polyhedra: Limits of Abstraction

Friedrich Eisenbrand, Thomas Rothvoss, Nicolai Hähnle

We investigate the diameter of a natural abstraction of the 1-skeleton of polyhedra. Although this abstraction is simpler than other abstractions that were previously studied in the literature, the best upper bounds on the diameter of polyhedra continue to ...

2009

Feature Extraction for Image Super-resolution using Finite Rate of Innovation Principles

Loïc Arnaud Baboulaz

To understand a real-world scene from several multiview pictures, it is necessary to find the disparities existing between each pair of images so that they are correctly related to one another., This process. called image registration, reguires the extract ...

Imperial College London2008

On Polyhedral Projection and Parametric Programming

Colin Neil Jones

This paper brings together two fundamental topics: polyhedral projection and parametric linear programming. First, it is shown that, given a parametric linear program (PLP), a polyhedron exists whose projection provides the solution to the PLP. Second, the ...

2008

Nonlinear dynamics of flute modes and self-organization phenomena in turbulent magnetized plasma

Costanza Zucca

A two-fields model that self-consistently describes the coupled, spectral dynamics of flute mode large-scale flows turbulence is presented. This model has a characteristic form of a 'predator-prey' system, in which the populations of flute mode quanta (pre ...

2007

The norm of the Euler class

Nicolas Monod

We prove that the norm of the Euler class

\mathcal{E}

for flat vector bundles is

2^{-n}

(in even dimension

n

, since it vanishes in odd dimension). This shows that the Sullivan-Smillie bound considered by Gromov and Ivanov-Turaev is sharp. We construc ...

Springer Verlag2012