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- 4 votes cast
Nov
9 |
awarded | Yearling |
Nov
9 |
accepted | Existence of the double coset ring on paper of Ihara |
Nov
9 |
asked | Existence of the double coset ring on paper of Ihara |
Nov
7 |
accepted | recovering information about a group from the spectrum of its Cayley graph |
Nov
6 |
comment |
is there a criterion for a two-generator subgroup of $PL(2,K)$ to be a cocompact lattice?
I would like to know how to prove that if $\gamma$ is an element of a torsion-free cocompact lattice in $PL(2,K)$ for $K$ a non-archimedean local field then the eigenvalues of $\gamma$ are in $K$. Ihara appears to make this claim in his article "Discrete subgroups of $PL(2,k_{\mathcal{P}})$. |
Nov
6 |
asked | recovering information about a group from the spectrum of its Cayley graph |
Nov
6 |
comment |
is there a criterion for a two-generator subgroup of $PL(2,K)$ to be a cocompact lattice?
Yes, I apologise, I think I was mistaken. I was told that there was a criterion like this in Beardon's book "The Geometry of Discrete Groups" but I am having difficulty locating any result like that in the book. |
Nov
6 |
awarded | Inquisitive |
Nov
5 |
asked | is there a criterion for a two-generator subgroup of $PL(2,K)$ to be a cocompact lattice? |
Nov
4 |
asked | In what sense is the function that maps $\alpha$ to the least $\alpha$-Erdős cardinal fast-growing |
Oct
22 |
comment |
Homogeneous polynomials of degree 3 in two variables
I did have a motivation for asking the question. I was interested in a question about the uniqueness of Polish group topologies on a semi-direct product of a simple Lie group with a vector space over R via one of its faithful representations. I'm afraid I can't remember all the details of exactly how this question came up but it would have helped me to prove the existence of a unique Polish group topology for a certain semi-direct product of Lie groups. |
Aug
3 |
comment |
roots in a root system which have nonzero coefficients with respect to each simple root
Is there any place on the internet or in the literature where all the roots in the $E_6$, $E_7$ or $E_8$ root systems are written out explicitly as linear combinations of simple roots? |
Aug
3 |
accepted | roots in a root system which have nonzero coefficients with respect to each simple root |
Jul
31 |
asked | roots in a root system which have nonzero coefficients with respect to each simple root |
Jun
23 |
accepted | Understanding how to construct Bruhat-Tits buildings for non-split groups by Galois descent |
Jun
23 |
asked | Understanding how to construct Bruhat-Tits buildings for non-split groups by Galois descent |
Jun
1 |
asked | artinian quotients of U(g) |
May
19 |
asked | Abelian subgroups of the automorphism group of a totally disconnected LCA group |
May
2 |
awarded | Supporter |
May
2 |
accepted | Arithmetic quotients of Bruhat-Tits buildings for groups over local fields of positive characteristic |