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Register a new userIterates of systems of operators in spaces of $omega$-ultradifferentiable functions
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Given two systems $P=(P_j(D))_{j=1}^N$ and $Q=(Q_j(D))_{j=1}^M$ of linear partial differential operators with constant coefficients, we consider the spaces ${mathcal E}_omega^P$ and ${mathcal E}_omega^Q$ of $omega$-ultradifferentiable functions with respect to the iterates of the systems $P$ and $Q$ respectively. We find necessary and sufficient conditions, on the systems and on the weights $omega(t)$ and $sigma(t)$, for the inclusion ${mathcal E}_omega^Psubseteq{mathcal E}_sigma^Q$. As a consequence we have a generalization of the classical Theorem of the Iterates.
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We study weighted $(PLB)$-spaces of ultradifferentiable functions defined via a weight function (in the sense of Braun, Meise and Taylor) and a weight system. We characterize when such spaces are ultrabornological in terms of the defining weight system. This generalizes Grothendiecks classical result that the space $mathcal{O}_M$ of slowly increasing smooth functions is ultrabornological to the context of ultradifferentiable functions. Furthermore, we determine the multiplier spaces of Gelfand-Shilov spaces and, by using the above result, characterize when such spaces are ultrabornological. In particular, we show that the multiplier space of the space of Fourier ultrahyperfunctions is ultrabornological, whereas the one of the space of Fourier hyperfunctions is not.
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We provide a projective description of the space $mathcal{E}^{{mathfrak{M}}}(Omega)$ of ultradifferentiable functions of Roumieu type, where $Omega$ is an arbitrary open set in $mathbb{R}^d$ and $mathfrak{M}$ is a weight matrix satisfying the analogue of Komatsus condition $(M.2)$. In particular, we obtain in a unified way projective descriptions of ultradifferentiable classes defined via a single weight sequence (Denjoy-Carleman approach) and via a weight function (Braun-Meise-Taylor approach) under considerably weaker assumptions than in earli
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