Über den 4-Rank der Klassengruppe quadratischer Zahlkörper
Let \(r^+_4(d)\) be the 4-rank of the strict class group of the quadratic field \(\mathbb{Q}(\sqrt{d})\). The author investigates the variation in \(r^+_4(d)\) when \(d\) is replaced by \(-d\) or by \(\pm p d\), \(p\) a rational prime. In particular, he gives a new proof of the theorem of P. Damey and J. Martinet, that \[ r^+_4(d) \le r^+_4(-d) \le r^+_4(d)+1,\quad d>0. \]
scientific article; zbMATH DE number 3863310