Top Network Posts

• 23 For which $n$ is it true that all surjections $SL_2(\mathbb{Z})\rightarrow SL_2(\mathbb{Z}/n\mathbb{Z})$ have kernel $\Gamma(n)$?
• 22 Is $\widehat{\mathbb{Z}}[[t]]\cong\widehat{\mathbb{Z}}[[\widehat{\mathbb{Z}}]]$?
• 21 morphisms representable by algebraic spaces vs morphisms representable by schemes
• 18 Do automorphisms of a finitely generated free module restrict to automorphisms on every invariant submodule?
• 15 Is every normal subgroup of $SL_2(\mathbb{Z}/n)$ also normal inside $GL_2(\mathbb{Z}/n)$?
• 12 When is the inverse image of the structure sheaf the structure sheaf?
• 11 Are there open subgroups of $SL_2(\widehat{\mathbb{Z}})$ which are $GL_2(\widehat{\mathbb{Z}})$-conjugate, but not $SL_2$-conjugate?
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