Lifts of projective congruence groups
نویسندگان
چکیده
منابع مشابه
Lifts of projective congruence groups
We show that noncongruence subgroups of SL2(Z) projectively equivalent to congruence subgroups are ubiquitous. More precisely, they always exist if the congruence subgroup in question is a principal congruence subgroup Γ(N) of level N > 2, and they exist in many cases also for Γ0(N). The motivation for asking this question is related to modular forms: projectively equivalent groups have the sam...
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ژورنال
عنوان ژورنال: Journal of the London Mathematical Society
سال: 2010
ISSN: 0024-6107
DOI: 10.1112/jlms/jdq062