Even sets of nodes and Gauss genus theory

2021/06/29 by Arnaud Beauville, Beauville, Arnaud
Mathematics · #Algebraic Geometry (math.AG) #FOS: Mathematics #math.AG

paper · pdf · doi:10.48550/arxiv.2106.15667

2 references added

arxiv created 2021/08/30 · arxiv updated 2021/08/31

Abstract

We observe that a lemma used in the study of even sets of nodes on surfaces applies almost verbatim to prove a celebrated formula of Gauss on the 2-torsion of the class group of a quadratic field.

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