Generalized Fourier expansions for zero-solutions of surjective convolution operators on \mathcal D\'(R) and \mathcal D\'_ω(R)


Abstract


It is well-known that each distribution \mu with compact support can be convolved with an arbitrary distribution and that this defines a convolution operator S_\mu, acting on \mathcal D'(R).The surjectivity of S_\mu, was characterized by Ehrenpreis [5]. Extending this result,we characterize in the present article the surjectivity of convolution operators on the space \mathcal D'(R) of all w-ultradistributions of Beurling type on R.This is done in two steps. In the first one we show that kerS_\mu has an absolute basis whenever S_\mu, admits a fundamental solution \nu∈ \mathcal D'<sub>w</sub>(R). The expansion of an element in kerS_\mu, with respect to this basis can be regarded as a generalization of the Fourier expansion of periodic ultradistributions.In the second step we use this sequence space representation together with results of Palamodov [15] and Vogt [17], [18] on the projective limit functor to obtain the desired characterization.It turns out that S_\mu is surjective if and only if S_\mu admits a fundamental solution. Hence the elements of kerS_\mu admit a generalized Fourier expansion for each surjective convolution operator S_\mu on \mathcal D'(R).Note that this differs from the behavior of convolution operators on the space \varepsilon_{{w}}(R) of w-ultradifferentiable functions of Roumieu-type, as Braun,Meise and Vogt [4] have shown. Note also that the results of the present article apply to convolution operators on \mathcal D'(R),too.

DOI Code: 10.1285/i15900932v10supn1p251

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