What is the moduli space of $ntimes n$ matrices with values on some field $k$ under conjugation?












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Maybe we can start with an easy example. I want to understand what is the moduli space of say $1times 1$ matrices under conjugation. So if such a matrix is $A$, the conjugation means $A = G^{-1}AG$ where say $Gin GL_n$. What is the moduli space then? And what is the corresponding moduli space for $2times 2$ such matrices? Let's say that $k = mathbb{C}$. What is the moduli space for $n times n$ such matrices? And do singularities appear?



This is the first question a speaker asked at a seminar last week. And I really want to understand not only what the moduli space of such matrices is but also when and why singularities appear.










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$endgroup$








  • 1




    $begingroup$
    Do you mean, What is the structure of the space $M_n(k) / sim$, where $A sim B$ if $A$ and $B$ are similar?
    $endgroup$
    – Travis
    Nov 2 '15 at 20:12












  • $begingroup$
    Was that a rethorical question? If so, you could try asking the speaker him/herself...
    $endgroup$
    – A.P.
    Nov 2 '15 at 20:14






  • 2




    $begingroup$
    No, I'm asking OP to verify that this is precisely what they mean by moduli space here. (Or is interpreting what the speaker meant by this term part of OP's question?)
    $endgroup$
    – Travis
    Nov 2 '15 at 20:19






  • 2




    $begingroup$
    You made me smile @Travis. My question was directed at the OP, regarding the intent behind the speaker's question. :)
    $endgroup$
    – A.P.
    Nov 2 '15 at 20:27






  • 3




    $begingroup$
    Mumford has a beautiful expository paper about this. dam.brown.edu/people/mumford/alg_geom/papers/…
    $endgroup$
    – Fredrik Meyer
    Nov 2 '15 at 21:53
















1












$begingroup$


Maybe we can start with an easy example. I want to understand what is the moduli space of say $1times 1$ matrices under conjugation. So if such a matrix is $A$, the conjugation means $A = G^{-1}AG$ where say $Gin GL_n$. What is the moduli space then? And what is the corresponding moduli space for $2times 2$ such matrices? Let's say that $k = mathbb{C}$. What is the moduli space for $n times n$ such matrices? And do singularities appear?



This is the first question a speaker asked at a seminar last week. And I really want to understand not only what the moduli space of such matrices is but also when and why singularities appear.










share|cite|improve this question









$endgroup$








  • 1




    $begingroup$
    Do you mean, What is the structure of the space $M_n(k) / sim$, where $A sim B$ if $A$ and $B$ are similar?
    $endgroup$
    – Travis
    Nov 2 '15 at 20:12












  • $begingroup$
    Was that a rethorical question? If so, you could try asking the speaker him/herself...
    $endgroup$
    – A.P.
    Nov 2 '15 at 20:14






  • 2




    $begingroup$
    No, I'm asking OP to verify that this is precisely what they mean by moduli space here. (Or is interpreting what the speaker meant by this term part of OP's question?)
    $endgroup$
    – Travis
    Nov 2 '15 at 20:19






  • 2




    $begingroup$
    You made me smile @Travis. My question was directed at the OP, regarding the intent behind the speaker's question. :)
    $endgroup$
    – A.P.
    Nov 2 '15 at 20:27






  • 3




    $begingroup$
    Mumford has a beautiful expository paper about this. dam.brown.edu/people/mumford/alg_geom/papers/…
    $endgroup$
    – Fredrik Meyer
    Nov 2 '15 at 21:53














1












1








1


1



$begingroup$


Maybe we can start with an easy example. I want to understand what is the moduli space of say $1times 1$ matrices under conjugation. So if such a matrix is $A$, the conjugation means $A = G^{-1}AG$ where say $Gin GL_n$. What is the moduli space then? And what is the corresponding moduli space for $2times 2$ such matrices? Let's say that $k = mathbb{C}$. What is the moduli space for $n times n$ such matrices? And do singularities appear?



This is the first question a speaker asked at a seminar last week. And I really want to understand not only what the moduli space of such matrices is but also when and why singularities appear.










share|cite|improve this question









$endgroup$




Maybe we can start with an easy example. I want to understand what is the moduli space of say $1times 1$ matrices under conjugation. So if such a matrix is $A$, the conjugation means $A = G^{-1}AG$ where say $Gin GL_n$. What is the moduli space then? And what is the corresponding moduli space for $2times 2$ such matrices? Let's say that $k = mathbb{C}$. What is the moduli space for $n times n$ such matrices? And do singularities appear?



This is the first question a speaker asked at a seminar last week. And I really want to understand not only what the moduli space of such matrices is but also when and why singularities appear.







linear-algebra algebraic-geometry moduli-space






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share|cite|improve this question











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asked Nov 2 '15 at 19:05









MarionMarion

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825618








  • 1




    $begingroup$
    Do you mean, What is the structure of the space $M_n(k) / sim$, where $A sim B$ if $A$ and $B$ are similar?
    $endgroup$
    – Travis
    Nov 2 '15 at 20:12












  • $begingroup$
    Was that a rethorical question? If so, you could try asking the speaker him/herself...
    $endgroup$
    – A.P.
    Nov 2 '15 at 20:14






  • 2




    $begingroup$
    No, I'm asking OP to verify that this is precisely what they mean by moduli space here. (Or is interpreting what the speaker meant by this term part of OP's question?)
    $endgroup$
    – Travis
    Nov 2 '15 at 20:19






  • 2




    $begingroup$
    You made me smile @Travis. My question was directed at the OP, regarding the intent behind the speaker's question. :)
    $endgroup$
    – A.P.
    Nov 2 '15 at 20:27






  • 3




    $begingroup$
    Mumford has a beautiful expository paper about this. dam.brown.edu/people/mumford/alg_geom/papers/…
    $endgroup$
    – Fredrik Meyer
    Nov 2 '15 at 21:53














  • 1




    $begingroup$
    Do you mean, What is the structure of the space $M_n(k) / sim$, where $A sim B$ if $A$ and $B$ are similar?
    $endgroup$
    – Travis
    Nov 2 '15 at 20:12












  • $begingroup$
    Was that a rethorical question? If so, you could try asking the speaker him/herself...
    $endgroup$
    – A.P.
    Nov 2 '15 at 20:14






  • 2




    $begingroup$
    No, I'm asking OP to verify that this is precisely what they mean by moduli space here. (Or is interpreting what the speaker meant by this term part of OP's question?)
    $endgroup$
    – Travis
    Nov 2 '15 at 20:19






  • 2




    $begingroup$
    You made me smile @Travis. My question was directed at the OP, regarding the intent behind the speaker's question. :)
    $endgroup$
    – A.P.
    Nov 2 '15 at 20:27






  • 3




    $begingroup$
    Mumford has a beautiful expository paper about this. dam.brown.edu/people/mumford/alg_geom/papers/…
    $endgroup$
    – Fredrik Meyer
    Nov 2 '15 at 21:53








1




1




$begingroup$
Do you mean, What is the structure of the space $M_n(k) / sim$, where $A sim B$ if $A$ and $B$ are similar?
$endgroup$
– Travis
Nov 2 '15 at 20:12






$begingroup$
Do you mean, What is the structure of the space $M_n(k) / sim$, where $A sim B$ if $A$ and $B$ are similar?
$endgroup$
– Travis
Nov 2 '15 at 20:12














$begingroup$
Was that a rethorical question? If so, you could try asking the speaker him/herself...
$endgroup$
– A.P.
Nov 2 '15 at 20:14




$begingroup$
Was that a rethorical question? If so, you could try asking the speaker him/herself...
$endgroup$
– A.P.
Nov 2 '15 at 20:14




2




2




$begingroup$
No, I'm asking OP to verify that this is precisely what they mean by moduli space here. (Or is interpreting what the speaker meant by this term part of OP's question?)
$endgroup$
– Travis
Nov 2 '15 at 20:19




$begingroup$
No, I'm asking OP to verify that this is precisely what they mean by moduli space here. (Or is interpreting what the speaker meant by this term part of OP's question?)
$endgroup$
– Travis
Nov 2 '15 at 20:19




2




2




$begingroup$
You made me smile @Travis. My question was directed at the OP, regarding the intent behind the speaker's question. :)
$endgroup$
– A.P.
Nov 2 '15 at 20:27




$begingroup$
You made me smile @Travis. My question was directed at the OP, regarding the intent behind the speaker's question. :)
$endgroup$
– A.P.
Nov 2 '15 at 20:27




3




3




$begingroup$
Mumford has a beautiful expository paper about this. dam.brown.edu/people/mumford/alg_geom/papers/…
$endgroup$
– Fredrik Meyer
Nov 2 '15 at 21:53




$begingroup$
Mumford has a beautiful expository paper about this. dam.brown.edu/people/mumford/alg_geom/papers/…
$endgroup$
– Fredrik Meyer
Nov 2 '15 at 21:53










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