Similar/Equivalent matrices and field extensions












2












$begingroup$


Let $F$ be a field and $F' supseteq F$ be a field extension. Suppose $A, B in M_n(F)$ are equivalent in $M_n(F')$, so there exist $P, Q in GL_n(F')$ such that $A = PBQ$. Is it necessarily true that $A$ and $B$ are equivalent in $M_n(F)$?



How about if "equivalent" is replaced with "similar"?










share|cite|improve this question









$endgroup$








  • 1




    $begingroup$
    For "similar", it is true and is a particular case of mathoverflow.net/questions/9162/… .
    $endgroup$
    – darij grinberg
    Dec 4 '18 at 0:43






  • 1




    $begingroup$
    For "equivalent" (I think the standard word for this is "congruent"), it is true because each matrix is equivalent to its rank normal form (and of course, the rank of a matrix does not change when we extend the field).
    $endgroup$
    – darij grinberg
    Dec 4 '18 at 0:44










  • $begingroup$
    Thanks for the replies! Very helpful.
    $endgroup$
    – Jeremiah Goertz
    Dec 5 '18 at 1:52
















2












$begingroup$


Let $F$ be a field and $F' supseteq F$ be a field extension. Suppose $A, B in M_n(F)$ are equivalent in $M_n(F')$, so there exist $P, Q in GL_n(F')$ such that $A = PBQ$. Is it necessarily true that $A$ and $B$ are equivalent in $M_n(F)$?



How about if "equivalent" is replaced with "similar"?










share|cite|improve this question









$endgroup$








  • 1




    $begingroup$
    For "similar", it is true and is a particular case of mathoverflow.net/questions/9162/… .
    $endgroup$
    – darij grinberg
    Dec 4 '18 at 0:43






  • 1




    $begingroup$
    For "equivalent" (I think the standard word for this is "congruent"), it is true because each matrix is equivalent to its rank normal form (and of course, the rank of a matrix does not change when we extend the field).
    $endgroup$
    – darij grinberg
    Dec 4 '18 at 0:44










  • $begingroup$
    Thanks for the replies! Very helpful.
    $endgroup$
    – Jeremiah Goertz
    Dec 5 '18 at 1:52














2












2








2


1



$begingroup$


Let $F$ be a field and $F' supseteq F$ be a field extension. Suppose $A, B in M_n(F)$ are equivalent in $M_n(F')$, so there exist $P, Q in GL_n(F')$ such that $A = PBQ$. Is it necessarily true that $A$ and $B$ are equivalent in $M_n(F)$?



How about if "equivalent" is replaced with "similar"?










share|cite|improve this question









$endgroup$




Let $F$ be a field and $F' supseteq F$ be a field extension. Suppose $A, B in M_n(F)$ are equivalent in $M_n(F')$, so there exist $P, Q in GL_n(F')$ such that $A = PBQ$. Is it necessarily true that $A$ and $B$ are equivalent in $M_n(F)$?



How about if "equivalent" is replaced with "similar"?







linear-algebra abstract-algebra






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Dec 4 '18 at 0:12









Jeremiah GoertzJeremiah Goertz

313




313








  • 1




    $begingroup$
    For "similar", it is true and is a particular case of mathoverflow.net/questions/9162/… .
    $endgroup$
    – darij grinberg
    Dec 4 '18 at 0:43






  • 1




    $begingroup$
    For "equivalent" (I think the standard word for this is "congruent"), it is true because each matrix is equivalent to its rank normal form (and of course, the rank of a matrix does not change when we extend the field).
    $endgroup$
    – darij grinberg
    Dec 4 '18 at 0:44










  • $begingroup$
    Thanks for the replies! Very helpful.
    $endgroup$
    – Jeremiah Goertz
    Dec 5 '18 at 1:52














  • 1




    $begingroup$
    For "similar", it is true and is a particular case of mathoverflow.net/questions/9162/… .
    $endgroup$
    – darij grinberg
    Dec 4 '18 at 0:43






  • 1




    $begingroup$
    For "equivalent" (I think the standard word for this is "congruent"), it is true because each matrix is equivalent to its rank normal form (and of course, the rank of a matrix does not change when we extend the field).
    $endgroup$
    – darij grinberg
    Dec 4 '18 at 0:44










  • $begingroup$
    Thanks for the replies! Very helpful.
    $endgroup$
    – Jeremiah Goertz
    Dec 5 '18 at 1:52








1




1




$begingroup$
For "similar", it is true and is a particular case of mathoverflow.net/questions/9162/… .
$endgroup$
– darij grinberg
Dec 4 '18 at 0:43




$begingroup$
For "similar", it is true and is a particular case of mathoverflow.net/questions/9162/… .
$endgroup$
– darij grinberg
Dec 4 '18 at 0:43




1




1




$begingroup$
For "equivalent" (I think the standard word for this is "congruent"), it is true because each matrix is equivalent to its rank normal form (and of course, the rank of a matrix does not change when we extend the field).
$endgroup$
– darij grinberg
Dec 4 '18 at 0:44




$begingroup$
For "equivalent" (I think the standard word for this is "congruent"), it is true because each matrix is equivalent to its rank normal form (and of course, the rank of a matrix does not change when we extend the field).
$endgroup$
– darij grinberg
Dec 4 '18 at 0:44












$begingroup$
Thanks for the replies! Very helpful.
$endgroup$
– Jeremiah Goertz
Dec 5 '18 at 1:52




$begingroup$
Thanks for the replies! Very helpful.
$endgroup$
– Jeremiah Goertz
Dec 5 '18 at 1:52










0






active

oldest

votes











Your Answer





StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "69"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});














draft saved

draft discarded


















StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3024916%2fsimilar-equivalent-matrices-and-field-extensions%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























0






active

oldest

votes








0






active

oldest

votes









active

oldest

votes






active

oldest

votes
















draft saved

draft discarded




















































Thanks for contributing an answer to Mathematics Stack Exchange!


  • Please be sure to answer the question. Provide details and share your research!

But avoid



  • Asking for help, clarification, or responding to other answers.

  • Making statements based on opinion; back them up with references or personal experience.


Use MathJax to format equations. MathJax reference.


To learn more, see our tips on writing great answers.




draft saved


draft discarded














StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3024916%2fsimilar-equivalent-matrices-and-field-extensions%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown





















































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown

































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown







Popular posts from this blog

Quarter-circle Tiles

build a pushdown automaton that recognizes the reverse language of a given pushdown automaton?

Mont Emei