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JOURNALS // Izvestiya Rossiiskoi Akademii Nauk. Seriya Matematicheskaya // Archive

Izv. Akad. Nauk SSSR Ser. Mat., 1981 Volume 45, Issue 4, Pages 775–792 (Mi im1585)

Class numbers in the genus of quadratic forms, and algebraic groups

A. S. Rapinchuk


Abstract: In this paper the class numbers $c(f)$ of quadratic forms $f$ with coefficients in an algebraic number field $K$ are studied by the methods of the theory of algebraic groups. It is shown that if a form $f$ is positive definite, then for any natural number $r$ there exists a quadratic form $g_r$, $K$-equivalent to $f$, such that $c(g_r)$ is divisible by $r$. A generalization of this result to semisimple algebraic $K$-groups of compact type is also obtained.
Bibliography: 21 titles.

UDC: 513.6

MSC: 10C30, 20G25, 20G30

Received: 01.04.1981


 English version:
Mathematics of the USSR-Izvestiya, 1982, 19:1, 79–93

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