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The normalizer of Γ0(N) in PSL(2, ℝ)

Published online by Cambridge University Press:  18 May 2009

M. Akbas  and
D. Singerman
M. Akbas
Affiliation:
Faculty of Mathematical Studies, The University, Southampton.
D. Singerman
Affiliation:
Faculty of Mathematical Studies, The University, Southampton.
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Let Γ denote the modular group, consisting of the Möbius transformations

As usual we denote the above transformation by the matrix remembering that V and – V represent the same transformation. If N is a positive integer we let Γ0(N) denote the transformations for which c ≡ 0 mod N. Then Γ0(N) is a subgroup of index

the product being taken over all prime divisors of N.

Type
Research Article
Information
Glasgow Mathematical Journal , Volume 32 , Issue 3 , September 1990 , pp. 317 - 327
Copyright
Copyright © Glasgow Mathematical Journal Trust 1990

References

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