Nilpotent Lie groups and eigenfunction expansions of Schrödinger operators II
Andrzej Hulanicki, Joe Jenkins (1987)
Studia Mathematica
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Andrzej Hulanicki, Joe Jenkins (1987)
Studia Mathematica
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Piotr Graczyk (1991)
Studia Mathematica
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Let be a symmetric semigroup of stable measures on a homogeneous group, with smooth Lévy measure. Applying Malliavin calculus for jump processes we prove that the measures have smooth densities.
Cristiana Bondioli (1992)
Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni
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Nikolskii spaces were defined by way of translations on and by way of coordinate maps on a differentiable manifold. In this paper we prove that, for functions with compact support in , we get an equivalent definition if we replace translations by all isometries of . This result seems to justify a definition of Nikolskii type function spaces on riemannian manifolds by means of a transitive group of isometries (provided that one exists). By approximation theorems, we prove that - for...
Ewa Damek (1992)
Studia Mathematica
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Ewa Damek, Andrzej Hulanicki (1991)
Studia Mathematica
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On the domain S_a = {(x,e^b): x ∈ N, b ∈ ℝ, b > a} where N is a simply connected nilpotent Lie group, a certain N-left-invariant, second order, degenerate elliptic operator L is considered. N × {e^a} is the Poisson boundary for L-harmonic functions F, i.e. F is the Poisson integral F(xe^b) = ʃ_N f(xy)dμ^b_a(x), for an f in L^∞(N). The main theorem of the paper asserts that the maximal function M^a f(x) = sup{|ʃf(xy)dμ_a^b(y)| : b > a} is of weak type (1,1).
J. Michael Wilson (2003)
Publicacions Matemàtiques
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Jun Tateoka (1994)
Studia Mathematica
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C. Watari [12] obtained a simple characterization of Lipschitz classes on the dyadic group using the -modulus of continuity and the best approximation by Walsh polynomials. Onneweer and Weiyi [4] characterized homogeneous Besov spaces on locally compact Vilenkin groups, but there are still some gaps to be filled up. Our purpose is to give the characterization of Besov spaces by oscillations, atoms and others on the dyadic groups. As applications, we show a strong capacity inequality...
Michele Campiti (1992)
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze
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G. Sampson (1993)
Studia Mathematica
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We consider operators of the form with Ω(y,u) = K(y,u)h(y-u), where K is a Calderón-Zygmund kernel and (see (0.1) and (0.2)). We give necessary and sufficient conditions for such operators to map the Besov space (= B) into itself. In particular, all operators with , a > 0, a ≠ 1, map B into itself.