Bicovariograms and Euler characteristic of random fields excursions

Abstract : Let f be a C1 bivariate function with Lipschitz derivatives, and F = {x ∈ R2 : f(x) λ} an upper level set of f, with λ ∈ R. We present a new identity giving the Euler charac- teristic of F in terms of its three-points indicator functions. A bound on the number of connected components of F in terms of the values of f and its gradient, valid in higher dimensions, is also derived. In dimension 2, if f is a random field, this bound allows to pass the former identity to expectations if f’s partial derivatives have Lipschitz constants with finite moments of sufficiently high order, without requiring bounded conditional den- sities. This approach provides an expression of the mean Euler characteristic in terms of the field’s third order marginal. Sufficient conditions and explicit formulas are given for Gaussian fields, relaxing the usual C2 Morse hypothesis.
Type de document :
Pré-publication, Document de travail
MAP5 2015-30. 2015
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https://hal.archives-ouvertes.fr/hal-01207503
Contributeur : Raphael Lachieze-Rey <>
Soumis le : mercredi 15 novembre 2017 - 14:21:01
Dernière modification le : samedi 18 novembre 2017 - 01:12:26

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covariograms-excursions.pdf
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  • HAL Id : hal-01207503, version 3
  • ARXIV : 1510.00502

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Raphaël Lachièze-Rey, Raphaëllachì Eze-Rey. Bicovariograms and Euler characteristic of random fields excursions. MAP5 2015-30. 2015. 〈hal-01207503v3〉

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