Name for “the kernel lemma”?












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Lately I've been fascinated by the result that one might state slightly informally





Lemma. (In the context of linear algebra over a field.) If $p$ and $q$ are relatively prime polynomials and $T$ is a linear operator then $ker(pq(T))=ker(p(T))oplusker(q(T))$.





Follows easily from the fact that $F[x]$ is a PID; you can use it to start a proof of the existence of the Jordan Canonical Form, also for a proof that the solution to a constant-coefficient linear homogeneous DE is what it is.



Q: Does this result have a standard name? Or do we know who proved it?










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  • 2




    $begingroup$
    In my university it was called "primary decomposition", in fact it is a corollary of en.wikipedia.org/wiki/Primary_decomposition.
    $endgroup$
    – Ivan Di Liberti
    Jan 17 at 16:04
















7












$begingroup$


Lately I've been fascinated by the result that one might state slightly informally





Lemma. (In the context of linear algebra over a field.) If $p$ and $q$ are relatively prime polynomials and $T$ is a linear operator then $ker(pq(T))=ker(p(T))oplusker(q(T))$.





Follows easily from the fact that $F[x]$ is a PID; you can use it to start a proof of the existence of the Jordan Canonical Form, also for a proof that the solution to a constant-coefficient linear homogeneous DE is what it is.



Q: Does this result have a standard name? Or do we know who proved it?










share|cite|improve this question











$endgroup$








  • 2




    $begingroup$
    In my university it was called "primary decomposition", in fact it is a corollary of en.wikipedia.org/wiki/Primary_decomposition.
    $endgroup$
    – Ivan Di Liberti
    Jan 17 at 16:04














7












7








7





$begingroup$


Lately I've been fascinated by the result that one might state slightly informally





Lemma. (In the context of linear algebra over a field.) If $p$ and $q$ are relatively prime polynomials and $T$ is a linear operator then $ker(pq(T))=ker(p(T))oplusker(q(T))$.





Follows easily from the fact that $F[x]$ is a PID; you can use it to start a proof of the existence of the Jordan Canonical Form, also for a proof that the solution to a constant-coefficient linear homogeneous DE is what it is.



Q: Does this result have a standard name? Or do we know who proved it?










share|cite|improve this question











$endgroup$




Lately I've been fascinated by the result that one might state slightly informally





Lemma. (In the context of linear algebra over a field.) If $p$ and $q$ are relatively prime polynomials and $T$ is a linear operator then $ker(pq(T))=ker(p(T))oplusker(q(T))$.





Follows easily from the fact that $F[x]$ is a PID; you can use it to start a proof of the existence of the Jordan Canonical Form, also for a proof that the solution to a constant-coefficient linear homogeneous DE is what it is.



Q: Does this result have a standard name? Or do we know who proved it?







linear-algebra abstract-algebra reference-request math-history






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edited Jan 17 at 17:20







user635162

















asked Jan 17 at 16:00









David C. UllrichDavid C. Ullrich

61.8k44095




61.8k44095








  • 2




    $begingroup$
    In my university it was called "primary decomposition", in fact it is a corollary of en.wikipedia.org/wiki/Primary_decomposition.
    $endgroup$
    – Ivan Di Liberti
    Jan 17 at 16:04














  • 2




    $begingroup$
    In my university it was called "primary decomposition", in fact it is a corollary of en.wikipedia.org/wiki/Primary_decomposition.
    $endgroup$
    – Ivan Di Liberti
    Jan 17 at 16:04








2




2




$begingroup$
In my university it was called "primary decomposition", in fact it is a corollary of en.wikipedia.org/wiki/Primary_decomposition.
$endgroup$
– Ivan Di Liberti
Jan 17 at 16:04




$begingroup$
In my university it was called "primary decomposition", in fact it is a corollary of en.wikipedia.org/wiki/Primary_decomposition.
$endgroup$
– Ivan Di Liberti
Jan 17 at 16:04










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In French schools and universities it is called "Lemme des Noyaux" which is a translation of Kernel Lemma. It is one of the rare occasions where I find a page inthe french wikipedia with no english counterpart.



Here is a link to said page :
https://fr.wikipedia.org/wiki/Lemme_des_noyaux



I suspect it has its own page because it is a standard result in the linear algebra curriculum. Sadly i haven't found a name in english but calling it the Kernel Lemma is a good idea.






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    $begingroup$

    In French schools and universities it is called "Lemme des Noyaux" which is a translation of Kernel Lemma. It is one of the rare occasions where I find a page inthe french wikipedia with no english counterpart.



    Here is a link to said page :
    https://fr.wikipedia.org/wiki/Lemme_des_noyaux



    I suspect it has its own page because it is a standard result in the linear algebra curriculum. Sadly i haven't found a name in english but calling it the Kernel Lemma is a good idea.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      In French schools and universities it is called "Lemme des Noyaux" which is a translation of Kernel Lemma. It is one of the rare occasions where I find a page inthe french wikipedia with no english counterpart.



      Here is a link to said page :
      https://fr.wikipedia.org/wiki/Lemme_des_noyaux



      I suspect it has its own page because it is a standard result in the linear algebra curriculum. Sadly i haven't found a name in english but calling it the Kernel Lemma is a good idea.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        In French schools and universities it is called "Lemme des Noyaux" which is a translation of Kernel Lemma. It is one of the rare occasions where I find a page inthe french wikipedia with no english counterpart.



        Here is a link to said page :
        https://fr.wikipedia.org/wiki/Lemme_des_noyaux



        I suspect it has its own page because it is a standard result in the linear algebra curriculum. Sadly i haven't found a name in english but calling it the Kernel Lemma is a good idea.






        share|cite|improve this answer









        $endgroup$



        In French schools and universities it is called "Lemme des Noyaux" which is a translation of Kernel Lemma. It is one of the rare occasions where I find a page inthe french wikipedia with no english counterpart.



        Here is a link to said page :
        https://fr.wikipedia.org/wiki/Lemme_des_noyaux



        I suspect it has its own page because it is a standard result in the linear algebra curriculum. Sadly i haven't found a name in english but calling it the Kernel Lemma is a good idea.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 18 at 16:59









        NassoumoNassoumo

        812




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