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The Positive Supercyclicity Theorem.

F. León Saavedra (2004)

Extracta Mathematicae

We present some recent results related with supercyclic operators, also some of its consequences. We will finalize with new related questions.

The Quantum Birkhoff Normal Form and Spectral Asymptotics

San Vũ Ngọc (2006)

Journées Équations aux dérivées partielles

In this talk we explain a simple treatment of the quantum Birkhoff normal form for semiclassical pseudo-differential operators with smooth coefficients. The normal form is applied to describe the discrete spectrum in a generalised non-degenerate potential well, yielding uniform estimates in the energy E . This permits a detailed study of the spectrum in various asymptotic regions of the parameters ( E , ) , and gives improvements and new proofs for many of the results in the field. In the completely resonant...

The quasi-canonical solution operator to ¯ restricted to the Fock-space

Georg Schneider (2005)

Czechoslovak Mathematical Journal

We consider the solution operator S μ , ( p , q ) L 2 ( μ ) ( p , q ) to the ¯ -operator restricted to forms with coefficients in μ = f f is entire and n | f ( z ) | 2 d μ ( z ) < . Here μ , ( p , q ) denotes ( p , q ) -forms with coefficients in μ , L 2 ( μ ) is the corresponding L 2 -space and μ is a suitable rotation-invariant absolutely continuous finite measure. We will develop a general solution formula S to ¯ . This solution operator will have the property S v ( p , q ) v ( p , q + 1 ) . As an application of the solution formula we will be able to characterize compactness of the solution operator in terms of compactness of commutators...

The set of automorphisms of B(H) is topologically reflexive in B(B(H))

Lajos Molnár (1997)

Studia Mathematica

The aim of this paper is to prove the statement announced in the title which can be reformulated in the following way. Let H be a separable infinite-dimensional Hilbert space and let Φ: B(H) → B(H) be a continuous linear mapping with the property that for every A ∈ B(H) there exists a sequence ( Φ n ) of automorphisms of B(H) (depending on A) such that Φ ( A ) = l i m n Φ n ( A ) . Then Φ is an automorphism. Moreover, a similar statement holds for the set of all surjective isometries of B(H).

The solution of the Kato problem in two dimensions.

Steve Hofmann, Alan McIntosh (2002)

Publicacions Matemàtiques

We solve, in two dimensions, the "square root problem of Kato". That is, for L ≡ -div (A(x)∇), where A(x) is a 2 x 2 accretive matrix of bounded measurable complex coefficients, we prove that L1/2: L12(R2) → L2(R2).[Proceedings of the 6th International Conference on Harmonic Analysis and Partial Differential Equations, El Escorial (Madrid), 2002].

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