Displaying 361 – 380 of 2024

Showing per page

Comparison of the refined analytic and the Burghelea-Haller torsions

Maxim Braverman, Thomas Kappeler (2007)

Annales de l’institut Fourier

The refined analytic torsion associated to a flat vector bundle over a closed odd-dimensional manifold canonically defines a quadratic form τ on the determinant line of the cohomology. Both τ and the Burghelea-Haller torsion are refinements of the Ray-Singer torsion. We show that whenever the Burghelea-Haller torsion is defined it is equal to ± τ . As an application we obtain new results about the Burghelea-Haller torsion. In particular, we prove a weak version of the Burghelea-Haller conjecture relating...

Compositions of equi-dimensional fold maps

Yoshihiro Hirato, Masamichi Takase (2012)

Fundamenta Mathematicae

According to Ando's theorem, the oriented bordism group of fold maps of n-manifolds into n-space is isomorphic to the stable n-stem. Among such fold maps we define two geometric operations corresponding to the composition and to the Toda bracket in the stable stem through Ando's isomorphism. By using these operations we explicitly construct several fold maps with convenient properties, including a fold map which represents the generator of the stable 6-stem.

Computational aspects of robust Holt-Winters smoothing based on M -estimation

Christophe Croux, Sarah Gelper, Roland Fried (2008)

Applications of Mathematics

To obtain a robust version of exponential and Holt-Winters smoothing the idea of M -estimation can be used. The difficulty is the formulation of an easy-to-use recursive formula for its computation. A first attempt was made by Cipra (Robust exponential smoothing, J. Forecast. 11 (1992), 57–69). The recursive formulation presented there, however, is unstable. In this paper, a new recursive computing scheme is proposed. A simulation study illustrates that the new recursions result in smaller forecast...

Conformal curvature for the normal bundle of a conformal foliation

Angel Montesinos (1982)

Annales de l'institut Fourier

It is proved that the normal bundle of a distribution 𝒱 on a riemannian manifold admits a conformal curvature C if and only if 𝒱 is a conformal foliation. Then is conformally flat if and only if C vanishes. Also, the Pontrjagin classes of can be expressed in terms of C .

Currently displaying 361 – 380 of 2024