Displaying similar documents to “Semigroup commutators under differences (II).”

Hölder estimates and hypoellipticity

André Unterberger, Julianne Unterberger (1976)

Annales de l'institut Fourier

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The aim of this paper is to show how, in order to prove regularity theorems, Hölder estimates, i.e. estimates involving products of powers of different semi-norms, can be used as well as standard estimates, and may in some instances be casier to prove.

L estimates for degenerate elliptic equations.

Antonio Sánchez-Calle (1988)

Revista Matemática Iberoamericana

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In this note we are going to address the question of when a second order differential operator is controlled by a subelliptic second order differential operator.

Hypoelliptic differential operators

Lars Hörmander (1961)

Annales de l'institut Fourier

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On donne une condition suffisante pour l’hypoellipticité d’une équation différentielle à coefficients variables. La démonstration utilise une paramétrix construite par transformation de Fourier.

An X-ray transform estimate in R.

Izabella Laba, Terence Tao (2001)

Revista Matemática Iberoamericana

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We prove an x-ray estimate in general dimension which is a stronger version of Wolff's Kakeya estimate [12]. This generalizes the estimate in [13], which dealt with the n = 3 case.