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arXiv · 1809.08954

Galois extensions, positive involutions and an application to unitary space-time coding

Vincent Astier·Thomas Unger
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Abstract

We show that under certain conditions every maximal symmetric subfield of a central division algebra with positive unitary involution $(B,\tau)$ will be a Galois extension of the fixed field of $\tau$ and will "real split" $(B,\tau)$. As an application we show that a sufficient condition for the existence of positive involutions on certain crossed product division algebras, considered by Berhuy in the context of unitary space-time coding, is also necessary, proving that Berhuy's construction is optimal.

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Vincent Astier, Thomas Unger. 2018-09-24. Galois extensions, positive involutions and an application to unitary space-time coding. https://arxiv.org/abs/1809.08954

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