Intermediate Optimal Gevrey Exponents Occur

1996/03/24 by Michael Christ, Christ, Michael · 1 citation
Mathematics · #Holomorphic and Operator Theory #Mathematical Analysis and Transform Methods #Spectral Theory in Mathematical Physics #math.FA

paper · pdf · doi:10.48550/arxiv.math/9603213

arxiv created 1996/03/24 · arxiv updated 2009/11/30

Abstract

Hypoellipticity in Gevrey classes G^s is characterized for a simple family of sums of squares of vector fields satisfying the bracket hypothesis, with analytic coefficients. It is shown that hypoellipticity holds if and only if s is greater than or equal to an optimal exponent that may take on any rational value.

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