Annali di Matematica Pura ed Applicata

, Volume 65, Issue 1, pp 27–33 | Cite as

On a problem of G. Sansone

  • Morris Newman


It is proved that the members of a certain family of free subgroups of index 6n in the modular group Γ are congruence groups if and only if n=1, 2, 4, 8.


Modular Group Free Subgroup Congruence Group 
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  1. [1]
    I Reiner,Normal subgroups of the unimodular group. Illinois J. Math. 2, 142–144 (1958).zbMATHMathSciNetGoogle Scholar
  2. [2]
    G. Sansone,Problemi insoluti nella teoria delle sostituzioni lineari. Conv. Internaz. di Teoria dei Gruppi Finiti (Firenze 1960) 5.19. Edizione Cremonese Rome 1960.Google Scholar

Copyright information

© Nicola Zanichelli Editore 1964

Authors and Affiliations

  • Morris Newman

There are no affiliations available

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