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6:57 AM
The question Index of the congruence subgroups of $PGL_2(\mathbb{Z}_p)$ has the deprecated tag (abstract-algebra). Should it be simply removed, or should it be replaced by some other tag?
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Q: Index of the congruence subgroups of $PGL_2(\mathbb{Z}_p)$

MathStudentLet $\Gamma_n$ be the $n$-th congruence subgroup of $GL(2,\mathbb{Z}_p)$. So $\Gamma_n$ consists of matrices in $GL(2,\mathbb{Z}_p)$ which are congruent to the identity matrix modulo $p^n$. Let $Z(\Gamma_n)$ the the center of $\Gamma_n$. My question is to compute the index $[\Gamma_n/Z(\Gamma_n...

 
 
6 hours later…
12:30 PM
@MartinSleziak I see that the tag-excerpt for was recently edited (by S. Carnahan) to say that is is specifically for "regularity of solutions of PDEs".
 
 
3 hours later…
4:00 PM
0
Q: Model for "$\kappa$ limit cardinal iff $2^\kappa$ limit cardinal"

Dominic van der ZypenIs there a model of ${\sf (ZFC)}$ such that in the model we have that $\kappa$ is a limit cardinal if and only if $2^\kappa$ is a limit cardinal?

 

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