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$U_2$ homeomorphic to $S^3 \times S^1$, how? [duplicate]

Recently, I have been reading Linear Groups, chapter 9, from Michael Artin, Algebra book. There is a question in the exercise (Chapter 9, Exercise section 3, no.3.2), given as follows Prove that $U_2$ ...
T ghosh's user avatar
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1 answer
44 views

Understanding the Terminology of Closed Subsets in $GL(n, \mathbb{C})$

In the context of the general linear group $GL(n, \mathbb{C})$, we use specific terminology to describe closed subsets. I'm paying attention to two definitions, which I report here and which come from ...
Hola's user avatar
  • 359
-1 votes
1 answer
60 views

Quotient group structure of general linear group

I want to find all quotient group structure in $GL(\mathbb{R}^n)$, which is all n*n invertible matrix on real number. The quotient group structure in $GL(\mathbb{R}^n)$ means to find normal subgroup $...
Kongca's user avatar
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1 answer
110 views

When is the quotient of $\operatorname{GL}_n(\mathbb{R})$ by a discrete subgroup compact?

My question is exactly that on the title. I'm interested in the action of some (discrete) subgroup $H$ on $\operatorname{GL}_n(\mathbb{R})$ by left multiplication. For example, $H$ can be $\...
Bumblebee's user avatar
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0 answers
92 views

Show that as groups, $\mathrm{GL}(V)\cong\mathrm{GL}_n(\mathbb{F})$, with the isomorphism given by $\theta \mapsto A_\theta$

Show that as groups, $\mathrm{GL}(V)\cong\mathrm{GL}_n(\mathbb{F})$, with the isomorphism given by $\theta \mapsto A_\theta$. The notation can be found in my attempt. 1st Attempt: If $\dim_\mathbb{F} ...
Andrés de Fonollosa's user avatar
11 votes
1 answer
833 views

What are the continuous outer automorphisms of the general linear group?

Is the only continuous outer automorphism of $\operatorname{GL}(n, \mathbb{R})$ the transpose inverse map $g \mapsto (g^\intercal)^{-1}$? If not, what other continuous outer automorphisms are there?
Craig's user avatar
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0 votes
1 answer
184 views

Showing that the isomorphism of the general linear group of a vector space with the group of invertible matrices is smooth

This is Example 7.3(e) from John Lee's Introduction to Smooth Manifolds. If $V$ is any real or complex vector space, $GL(V)$ denotes the set of invertible linear maps from $V$ to itself. It is a group ...
nomadicmathematician's user avatar
1 vote
1 answer
59 views

Proof that $GL(n,\mathbb{C})$ is isomorphic to a properly embedded Lie subgroup of $GL(2n,\mathbb{R})$

Below is an example of embedded Lie Subgroup from John Lee's Introduction to Smooth Manifolds example 7.18 (d). In this example, why is the image of $\beta$ a properly embedded Lie subgroup of $GL(2n,\...
nomadicmathematician's user avatar
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1 answer
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Query Regarding the Proof of Z(SO(2m))={±1} in Section 3.7 of 'Naive Lie Theory' by John Stillwell

I have been reading John Stillwell's 'Naive Lie Theory' and in Section 3.7, the author tries to prove that $Z(SO(2m)) = {\pm 1}$. In the proof, a matrix $I^\star$ is introduced with the form: $$ I^\...
Hance Wu's user avatar
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42 views

Representations of general linear Lie algebra vs general linear group [duplicate]

I know that $\mathrm{GL}_{n}(\mathbb{C})$ is not simply connected. Therefore I don’t quite understand the correspondence between representations of $\mathrm{GL}_{n}(\mathbb{C})$ and $\mathfrak{gl}_{n}(...
Matthew Willow's user avatar
1 vote
1 answer
107 views

Why $SL$-invariants and highest weight vectors of rectangular shape coincide?

The groups $\mathrm{SL}(n) := \mathrm{SL}(n,\mathbb{C})$ and $\mathrm{GL}(n) = \mathrm{GL}(n,\mathbb{C})$ acts on $\mathbb{C}^n$ by multiplication from the left. This induces the diagonal action on $\...
SimB4's user avatar
  • 125
3 votes
1 answer
143 views

Is $GL(n)\otimes GL(n)$ is closed in $GL(n^2)$?

Let $GL(n) := \mathrm{GL}(n, \mathbb{C})$ - be space of invertible $n\times n$ matrices over $\mathbb{C}$, i.e. matrix Lie group. Let $H := GL(n) \otimes GL(n)$ be a group with multiplication given by ...
SimB4's user avatar
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2 votes
1 answer
253 views

$GL_n(C)$ is isomorphic to a lie subgroup of $GL(2n,R)$

$GL_n(C)$ is isomorphic to a lie subgroup of $GL_{2n}(R)$. I see some posts concerning this (not the same claim): $GL(n, \mathbb{C})$ is isomorphic to a subgroup of $GL(2n, \mathbb{R})$ $GL_n\mathbb{C}...
Mat999's user avatar
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Chapter 1, Exercise 12 in Brian Hall's Lie groups, Lie algebras, and representations

Suppose $A$ and $B$ are invertible $n \times n$ matrices. Show that there are only finitely many complex numbers $\lambda$ for which $\text{det}( \lambda A + (1-\lambda)B) = 0$. Show that there exists ...
AleNekro97's user avatar
2 votes
1 answer
1k views

Show that the general linear group $GL(n, \Bbb R)$ is a Lie group under matrix multiplication.

Show that the general linear group $GL(n, \Bbb R)$ is a Lie group under matrix multiplication. I'm reading an introduction to manifolds by Tu and found this problem there. The definition I have for a ...
Jasper's user avatar
  • 105
2 votes
1 answer
120 views

Are there holes in every neighbourhood in GL(n,R)?

$GL(n,\mathbb{R})$ can be seen as $\mathbb{R}^{n^2}$ with points of non invertible matrix removed which form "holes" in $\mathbb{R}^{n^2}$. These holes seems to be dense in $\mathbb{R}^{n^2}$...
jw_'s user avatar
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1 vote
0 answers
162 views

A question on the conclusion of the proof of "$Sl(2, \Bbb R)$ is transitive on the upper half plane".

$Sl(2, \Bbb R)$ is transitive on the upper half-plane. Here I have a question on the conclusion. I have proved that for any $w \in \Bbb H$ there exists $z \in \Bbb H$ s.t $A⋅z=w$ for some $A \in Sl(2, ...
Ri-Li's user avatar
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-2 votes
1 answer
333 views

$SL(2,\mathbb{C})\cong \operatorname{Spin}(1,3,\mathbb{R})?$ or $SL(2,\mathbb{C})\cong \operatorname{Spin}(3,1,\mathbb{R})?$ [closed]

Which one of the isomorphism is correct? $$SL(2,\mathbb{C})\cong \operatorname{Spin}(1,3,\mathbb{R})?$$ $$SL(2,\mathbb{C})\cong \operatorname{Spin}(3,1,\mathbb{R})?$$ If $SL(2,\mathbb{C})\cong \...
annie marie cœur's user avatar
3 votes
0 answers
162 views

A specific coset decomposition of $\mathrm{GL}_n(\mathbb{C})$

I am reading an old paper [1] where they introduce a specific decomposition of a complex, invertible matrix. There is no proof, so I am trying to come up with one. The claim goes as follows: Let $\...
Mads G's user avatar
  • 31
2 votes
1 answer
565 views

Closed subgroups of $GL(n, \mathbb{C})$

Let $M_{n}(\mathbb{C})$ be the space of all complex $n\times n$ matrices equipped with the operator norm: $$||A|| := \sup_{||x||\le 1}||Ax|| \quad A \in M_{n}(\mathbb{C})$$ Let $GL(n, \mathbb{C})$ be ...
JustWannaKnow's user avatar
0 votes
1 answer
289 views

$GL_n\mathbb{C}$ as subgroup of $GL_{2n}\mathbb{R}$

I am confused about the following paragraph in Fulton W., Harris J. "Representation Theory: A First Course": Of course, the group $GL_n\mathbb{C}$ of complex linear automorphisms of a ...
Motoko's user avatar
  • 35
0 votes
1 answer
215 views

about Cartan's theorem

theorem : Let $SL(n,\Bbb{C})$ be the group of matrices of complex entries and determinant $1$ then $SL(n,\Bbb{C})$ is a regular submanifold of $GL(n,\Bbb{C})$. proof : $GL(n,\mathbb{C})$ is a Lie ...
amir bahadory's user avatar
-1 votes
1 answer
305 views

How to determine the order of an element of Special Linear Group

Let, $S=\begin{pmatrix} 0 &-1 \\ 1 & 0 \end{pmatrix}$ and $T=\begin{pmatrix} 1 &1 \\ 0 & 1 \end{pmatrix}$ . The matrices $S$ and $T$ generate $SL_2(\mathbb Z)$. The matrix $...
Consider Non-Trivial Cases's user avatar
3 votes
2 answers
2k views

Generators for general / special linear groups

How do we determine the generators and relations for general / special linear groups over a finite field? I will be particularly interested in prime fields, in that also for $\mathbb{Z}_2$? I know ...
vidyarthi's user avatar
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1 vote
1 answer
78 views

How to show that $\begin{pmatrix} 0 & -x \\\ 1/x & 0\end{pmatrix}$ is conjugate to a rotation?

Let $x >0$, and set $A=\begin{pmatrix} 0 & -x \\\ 1/x & 0\end{pmatrix}$. Question: How to show that $A \in \operatorname{SL}_2(\mathbb R)$ is conjugate to an element of $\operatorname{SO}(2)...
Asaf Shachar's user avatar
  • 25.6k
4 votes
1 answer
291 views

$PSl_n(\mathbb{C})\cong PGl_n(\mathbb{C})$?

I was reading about projective linear groups because I was asked to show that $PSl_n(\mathbb{C})\cong PGl_n(\mathbb{C})$. Here $PSl_n(\mathbb{C})$ is the projective space of $Sl_n(\mathbb{C})$, i.e. $...
roi_saumon's user avatar
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0 votes
1 answer
132 views

Continuity of a Group Homomorphism, Representation of SU(2)

In page 82 of Brian C. Hall's Lie Groups, Lie Algebras and Representations, he establishes the following representation $\Pi_m$ of SU(2) on $V_m$, the space of homogeneous polynomials of degree $m$ in ...
horned-sphere's user avatar
0 votes
2 answers
71 views

Subspace Topology of $GL_n(\Bbb R)$

I'm trying to understand $GL_n(\mathbb R)$. I've read that we can think its topology with Euclidean metric. I know that $GL_n(\mathbb R)$ is a subspace of $Mat_n(\mathbb R)$ but I cannot understand ...
user519955's user avatar
  • 1,313
6 votes
1 answer
220 views

Which linear maps $\mathbb{R}^{n^2} \to \mathbb{R}^{n^2} $ map $\text{GL}_n$ into $\text{GL}_n$?

Can we characterize all linear maps $\mathbb{R}^{n^2} \to \mathbb{R}^{n^2} $ which map $\text{GL}_n$ into $\text{GL}_n$? In particular, is it true that every such map is given by $X \to AXB$ or $X \...
Asaf Shachar's user avatar
  • 25.6k
9 votes
2 answers
1k views

Irreducible finite dimensional complex representation of $GL_2(\Bbb C)$

I know the basic theory of representation theory of compact Lie groups and I want to understand a non-compact example: How to find all irreducible finite dimensional complex representations of $...
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