A Beurling-helson Type Theorem for Modulation Spaces

نویسندگان

KASSO A. OKOUDJOU

K. A. OKOUDJOU

چکیده

We prove a Beurling-Helson type theorem on modulation spaces. More precisely, we show that the only C changes of variables that leave invariant the modulation spaces M(R) are affine functions on R. A special case of our result involving the Sjöstrand algebra was considered earlier by A. Boulkhemair.

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