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Sept. 2001 On certain cohomology set for $\Gamma _0(N)$. II
Takashi Ono
Proc. Japan Acad. Ser. A Math. Sci. 77(7): 108-110 (Sept. 2001). DOI: 10.3792/pjaa.77.108


Let $G = \Gamma_0(N)$ and $g$ be the group generated by the involution $z \mapsto -1/Nz$ of the upper half plane. We determine the cohomology set $H^1(g,G)$ in terms of the class numbers $h(-N)$ and $h(-4N)$ of quadratic forms.


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Takashi Ono. "On certain cohomology set for $\Gamma _0(N)$. II." Proc. Japan Acad. Ser. A Math. Sci. 77 (7) 108 - 110, Sept. 2001.


Published: Sept. 2001
First available in Project Euclid: 23 May 2006

zbMATH: 1171.11313
MathSciNet: MR1857284
Digital Object Identifier: 10.3792/pjaa.77.108

Primary: 11F75

Keywords: binary quadratic forms , class number of orders , cohomology sets , Congruence subgroups of level $N$ , the involution

Rights: Copyright © 2001 The Japan Academy

Vol.77 • No. 7 • Sept. 2001
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