Signature morphisms from the Cremona group over a non-closed field

Signature morphisms from the Cremona group over a non-closed field cover
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Abstract

We prove that the plane Cremona group over a perfect field with at least one Galois extension of degree 8 is a non-trivial amalgam, and that it admits a surjective morphism to a free product of groups of order 2.

Cite this article

Stéphane Lamy, Susanna Zimmermann, Signature morphisms from the Cremona group over a non-closed field. J. Eur. Math. Soc. 22 (2020), no. 10, pp. 3133–3173

DOI 10.4171/JEMS/983