Torsion homology
Torsion homology
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Nicolas Bergeron, Inst铆tut de Math茅mat铆ques de Juss铆eu-Par铆s R铆ve Gaunche
Arithmetic groups --- that generalize the modular group --- can have'a lot' of torsion in their homology. Starting from the examples of congruence subgroups of the modular and Bianchi groups where homology reduces to abelianization, I will explain what 'a lot' means. I will then try to explain how this interacts with more classical question of number theory and geometry. This is joint work with Akshay Venkatesh and Mehmet Haluk Sengun.