On the Normalizer of the Congruence Subgroup H05(I) of the Hecke Group H5

Let l = 2 cos \frac{p}{5} and let H5 be the Hecke group associated to l. In this paper, the normalizers of the congruence subgroups H05(I) in PSL(2Z[l]) are studied in the case where I = (2)aI ', (2, I') = 1 and I' is a prime ideal.

Anahtar Kelimeler:

Normalizer, Congruence subgroup, Hecke group

On the Normalizer of the Congruence Subgroup H05(I) of the Hecke Group H5

Keywords:

Normalizer, Congruence subgroup, Hecke group,

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Department of Mathematics, Faculty of Science and Arts, Karadeniz Technical University, Trabzon-TURKEY e-mail: suzunktu@yahoo.com