The Kluvanek-Kantorovitz characterization of scalar operators in locally convex spaces.
The Kneser property for the abstract Cauchy problem
We establish existence of mild solutions for the semilinear first order functional abstract Cauchy problem and we prove that the set of mild solutions of this problem is connected in the space of continuous functions.
The Krein string and characteristic functions of non-self-adjoint operators.
The mapping problem for well-behaved convolutions
The Lagrange multipliers theorem for locally convex metric spaces
The laplacian and the Dirac operator in infinitely many variables
The laplacian and the discrete laplacian
The large deformation of nonlinearly elastic shells in axisymmetric flows
The Lax-Phillips infinitesimal generator and the scattering matrix for automorphic functions
We study the infinitesimal generator of the Lax-Phillips semigroup of the automorphic scattering system defined on the Poincaré upper half-plane for SL₂(ℤ). We show that its spectrum consists only of the poles of the resolvent of the generator, and coincides with the poles of the scattering matrix, counted with multiplicities. Using this we construct an operator whose eigenvalues, counted with algebraic multiplicities (i.e. dimensions of generalized eigenspaces), are precisely the non-trivial zeros...
The level crossing problem in semi-classical analysis I. The symmetric case
We describe a microlocal normal form for a symmetric system of pseudo-differential equations whose principal symbol is a real symmetric matrix with a generic crossing of eigenvalues. We use it in order to give a precise description of the microlocal solutions.
The Lévy laplacian and differential operators of 2-nd order in Hilbert spaces
We shall show that every differential operator of 2-nd order in a real separable Hilbert space can be decomposed into a regular and an irregular operator. Then we shall characterize irregular operators and differential operators satisfying the maximum principle. Results obtained for the Lévy laplacian in [3] will be generalized for irregular differential operators satisfying the maximum principle.
The linear modulus of an integral operator
The linear symmetric systems associated with the modified Cherednik operators and applications
We introduce and study the linear symmetric systems associated with the modified Cherednik operators. We prove the well-posedness results for the Cauchy problem for these systems. Eventually we describe the finite propagation speed property of it.
The linear-quadratic optimal control problem for delay differential equations
In questo lavoro si considera il problema del controllo ottimo per un'equazione lineare con ritardo in uno spazio di Hilbert, con costo quadratico. Si dimostra che il problema della sintesi si traduce in una equazione di Riccati in uno opportuno spazio prodotto e si prova che tale equazione ammette un’unica soluzione.
The Local Index Formula in Noncommutative Geometry.
The Local Stability of Positive Solutions to the Hammerstein Equation with a Nonmonotonic Nemytskii Operator.
The locally uniform nonsquare in generalized Cesàro sequence spaces.
The low energy expansion in nonrelativistic scattering theory
The mappings of degree 1.
The Marcinkiewicz multiplier condition for bilinear operators
This article is concerned with the question of whether Marcinkiewicz multipliers on give rise to bilinear multipliers on ℝⁿ × ℝⁿ. We show that this is not always the case. Moreover, we find necessary and sufficient conditions for such bilinear multipliers to be bounded. These conditions in particular imply that a slight logarithmic modification of the Marcinkiewicz condition gives multipliers for which the corresponding bilinear operators are bounded on products of Lebesgue and Hardy spaces.