Classification of normal subgroups of Hecke group H6 in terms of parabolic class number

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Yurttaş Güneş A., Demirci M., Cangül İ. N.

Numerical Analysis and Applied Mathematics, AIP Conf. Proc., , vol.1389, pp.315-316, 2011 (Peer-Reviewed Journal) identifier


In [3], Greenberg showed that n <= 6t(3) so that mu - nt <= 6t(4) for a normal subgroup N of level n and index mu having t parabolic classes in the modular group Gamma. Accola, [1], improved these to n <= 6t(2) always and n <= t(2) if Gamma/N is not abelian. Newman, [5], obtained another generalisation of these results. Hecke groups are generalisations of the modular group. We particularly deal with one of the most important cases, q = 6.