Transvection matrices generate $ operatorname{SL}_n(mathbb{R}) $












4












$begingroup$


I need to prove that the transvection matrices generate the special linear group $operatorname{SL}_n left(mathbb{R}right) $.



I want to proceed using induction on $n$.



I was able to prove the $2times 2$ case, but I am having difficulty with the $n+1$ case.



I supposed that the elementary matrices of the first type generate $operatorname{SL}_n(mathbb{R})$. And I want to show that an elementary matrix of the first type of order $n+1$ can generate $operatorname{SL}_{n+1}(mathbb{R})$










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  • 2




    $begingroup$
    Possible duplicate of What are the generators for $SL_n(mathbb{R})$ (Michael Artin's Algebra book)
    $endgroup$
    – user549397
    Jan 24 at 3:25
















4












$begingroup$


I need to prove that the transvection matrices generate the special linear group $operatorname{SL}_n left(mathbb{R}right) $.



I want to proceed using induction on $n$.



I was able to prove the $2times 2$ case, but I am having difficulty with the $n+1$ case.



I supposed that the elementary matrices of the first type generate $operatorname{SL}_n(mathbb{R})$. And I want to show that an elementary matrix of the first type of order $n+1$ can generate $operatorname{SL}_{n+1}(mathbb{R})$










share|cite|improve this question











$endgroup$








  • 2




    $begingroup$
    Possible duplicate of What are the generators for $SL_n(mathbb{R})$ (Michael Artin's Algebra book)
    $endgroup$
    – user549397
    Jan 24 at 3:25














4












4








4


3



$begingroup$


I need to prove that the transvection matrices generate the special linear group $operatorname{SL}_n left(mathbb{R}right) $.



I want to proceed using induction on $n$.



I was able to prove the $2times 2$ case, but I am having difficulty with the $n+1$ case.



I supposed that the elementary matrices of the first type generate $operatorname{SL}_n(mathbb{R})$. And I want to show that an elementary matrix of the first type of order $n+1$ can generate $operatorname{SL}_{n+1}(mathbb{R})$










share|cite|improve this question











$endgroup$




I need to prove that the transvection matrices generate the special linear group $operatorname{SL}_n left(mathbb{R}right) $.



I want to proceed using induction on $n$.



I was able to prove the $2times 2$ case, but I am having difficulty with the $n+1$ case.



I supposed that the elementary matrices of the first type generate $operatorname{SL}_n(mathbb{R})$. And I want to show that an elementary matrix of the first type of order $n+1$ can generate $operatorname{SL}_{n+1}(mathbb{R})$







matrices group-theory algebraic-k-theory






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edited Jan 23 at 12:46









amWhy

1




1










asked Sep 6 '13 at 10:30









CarpediemCarpediem

832632




832632








  • 2




    $begingroup$
    Possible duplicate of What are the generators for $SL_n(mathbb{R})$ (Michael Artin's Algebra book)
    $endgroup$
    – user549397
    Jan 24 at 3:25














  • 2




    $begingroup$
    Possible duplicate of What are the generators for $SL_n(mathbb{R})$ (Michael Artin's Algebra book)
    $endgroup$
    – user549397
    Jan 24 at 3:25








2




2




$begingroup$
Possible duplicate of What are the generators for $SL_n(mathbb{R})$ (Michael Artin's Algebra book)
$endgroup$
– user549397
Jan 24 at 3:25




$begingroup$
Possible duplicate of What are the generators for $SL_n(mathbb{R})$ (Michael Artin's Algebra book)
$endgroup$
– user549397
Jan 24 at 3:25










1 Answer
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$begingroup$

Multiplying a matrix on the left or the right by a transvection matrix corresponds to adding a multiple of one row/column to another row/column. So we just need to prove that we can reduce any matrix in ${rm SL}_n(K)$ to the identity matrix using row and column operations of this type. This works for any field $K$.



The proof is by induction on $n$ and there is nothing to prove for $n=1$, so assume that $n>1$. Let $A = (a_{ij}) in {rm SL}_n(K)$.




  1. If $a_{12} = 0$ then, choose some $j$ with $a_{1j} ne 0$ and add column $j$ to column $2$ to get $a_{12} ne 0$.


  2. Subtract $(a_{11}-1)/a_{12}$ times column $2$ from column $1$ to get $a_{11}=1$.


  3. For all $j>1$ subtract $a_{1j}$ times column $1$ from column $j$ to get $a_{1j}=0$. Similarly use row operations to get $a_{j1}=0$ for all $j>1$.



You have now reduced to the case $n-1$.






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    $begingroup$

    Multiplying a matrix on the left or the right by a transvection matrix corresponds to adding a multiple of one row/column to another row/column. So we just need to prove that we can reduce any matrix in ${rm SL}_n(K)$ to the identity matrix using row and column operations of this type. This works for any field $K$.



    The proof is by induction on $n$ and there is nothing to prove for $n=1$, so assume that $n>1$. Let $A = (a_{ij}) in {rm SL}_n(K)$.




    1. If $a_{12} = 0$ then, choose some $j$ with $a_{1j} ne 0$ and add column $j$ to column $2$ to get $a_{12} ne 0$.


    2. Subtract $(a_{11}-1)/a_{12}$ times column $2$ from column $1$ to get $a_{11}=1$.


    3. For all $j>1$ subtract $a_{1j}$ times column $1$ from column $j$ to get $a_{1j}=0$. Similarly use row operations to get $a_{j1}=0$ for all $j>1$.



    You have now reduced to the case $n-1$.






    share|cite|improve this answer











    $endgroup$


















      10












      $begingroup$

      Multiplying a matrix on the left or the right by a transvection matrix corresponds to adding a multiple of one row/column to another row/column. So we just need to prove that we can reduce any matrix in ${rm SL}_n(K)$ to the identity matrix using row and column operations of this type. This works for any field $K$.



      The proof is by induction on $n$ and there is nothing to prove for $n=1$, so assume that $n>1$. Let $A = (a_{ij}) in {rm SL}_n(K)$.




      1. If $a_{12} = 0$ then, choose some $j$ with $a_{1j} ne 0$ and add column $j$ to column $2$ to get $a_{12} ne 0$.


      2. Subtract $(a_{11}-1)/a_{12}$ times column $2$ from column $1$ to get $a_{11}=1$.


      3. For all $j>1$ subtract $a_{1j}$ times column $1$ from column $j$ to get $a_{1j}=0$. Similarly use row operations to get $a_{j1}=0$ for all $j>1$.



      You have now reduced to the case $n-1$.






      share|cite|improve this answer











      $endgroup$
















        10












        10








        10





        $begingroup$

        Multiplying a matrix on the left or the right by a transvection matrix corresponds to adding a multiple of one row/column to another row/column. So we just need to prove that we can reduce any matrix in ${rm SL}_n(K)$ to the identity matrix using row and column operations of this type. This works for any field $K$.



        The proof is by induction on $n$ and there is nothing to prove for $n=1$, so assume that $n>1$. Let $A = (a_{ij}) in {rm SL}_n(K)$.




        1. If $a_{12} = 0$ then, choose some $j$ with $a_{1j} ne 0$ and add column $j$ to column $2$ to get $a_{12} ne 0$.


        2. Subtract $(a_{11}-1)/a_{12}$ times column $2$ from column $1$ to get $a_{11}=1$.


        3. For all $j>1$ subtract $a_{1j}$ times column $1$ from column $j$ to get $a_{1j}=0$. Similarly use row operations to get $a_{j1}=0$ for all $j>1$.



        You have now reduced to the case $n-1$.






        share|cite|improve this answer











        $endgroup$



        Multiplying a matrix on the left or the right by a transvection matrix corresponds to adding a multiple of one row/column to another row/column. So we just need to prove that we can reduce any matrix in ${rm SL}_n(K)$ to the identity matrix using row and column operations of this type. This works for any field $K$.



        The proof is by induction on $n$ and there is nothing to prove for $n=1$, so assume that $n>1$. Let $A = (a_{ij}) in {rm SL}_n(K)$.




        1. If $a_{12} = 0$ then, choose some $j$ with $a_{1j} ne 0$ and add column $j$ to column $2$ to get $a_{12} ne 0$.


        2. Subtract $(a_{11}-1)/a_{12}$ times column $2$ from column $1$ to get $a_{11}=1$.


        3. For all $j>1$ subtract $a_{1j}$ times column $1$ from column $j$ to get $a_{1j}=0$. Similarly use row operations to get $a_{j1}=0$ for all $j>1$.



        You have now reduced to the case $n-1$.







        share|cite|improve this answer














        share|cite|improve this answer



        share|cite|improve this answer








        edited Nov 29 '16 at 9:47









        darij grinberg

        11.1k33167




        11.1k33167










        answered Sep 6 '13 at 10:49









        Derek HoltDerek Holt

        53.8k53571




        53.8k53571






























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