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Carnot spaces and the k-stein condition

  • María J Druetta EMAIL logo
Published/Copyright: August 10, 2006
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Advances in Geometry
From the journal Volume 6 Issue 3

Abstract

A riemannian manifold M with associated Jacobi operators RX (RXY = R(Y, X) X), X in TM, is said to be k-stein, k ≥ 1, if there exists a function μk on M such that tr(RkX) = μk|X|2k for all X in TM. We study the k-stein condition on Lie groups of Iwasawa type and in particular in those which are Carnot spaces. We show that a Carnot space which is k-stein for some k > 1 is necessarily a Damek–Ricci space; Damek–Ricci spaces are Einstein and 2-stein and they are not k-stein for any k ≥ 3, unless they are symmetric. Moreover, we show that a harmonic Lie group of Iwasawa type which is 3-stein is a symmetric space of noncompact type and rank one.


(Communicated by P. Eberlein)


Received: 2004-08-03
Revised: 2005-03-01
Published Online: 2006-08-10
Published in Print: 2006-07-01

© Walter de Gruyter

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