Are there any references on linear algebra (module theory) over non unital rings?












4












$begingroup$


Are there any references on linear algebra (module theory) over non unital rings? What are the main differences with unital rings in that respect?










share|cite|improve this question









$endgroup$












  • $begingroup$
    The main difference is that almost nothing works. The reason is simple: defining $rx=0$ for every $rin R$ and every $xin A$ defines an $R$-module structure on the abelian group $A$. Something better happens when you require that $RA=A$, in order that $A$ is a module.
    $endgroup$
    – egreg
    Jan 15 at 23:20












  • $begingroup$
    Can you elaborate on this simple reason?
    $endgroup$
    – Patrick Sole
    Jan 15 at 23:26








  • 1




    $begingroup$
    @PatrickSole doesn’t it seem a little bad that every Abelian group is a (nonunitary) module over every rng? That’s certainly not the case for unitary modules.
    $endgroup$
    – rschwieb
    Jan 16 at 0:47










  • $begingroup$
    Things break down severely. This is more or less the reason why I insist that rings should have multiplicative neutral elements :-)
    $endgroup$
    – Jyrki Lahtonen
    Jan 17 at 22:54
















4












$begingroup$


Are there any references on linear algebra (module theory) over non unital rings? What are the main differences with unital rings in that respect?










share|cite|improve this question









$endgroup$












  • $begingroup$
    The main difference is that almost nothing works. The reason is simple: defining $rx=0$ for every $rin R$ and every $xin A$ defines an $R$-module structure on the abelian group $A$. Something better happens when you require that $RA=A$, in order that $A$ is a module.
    $endgroup$
    – egreg
    Jan 15 at 23:20












  • $begingroup$
    Can you elaborate on this simple reason?
    $endgroup$
    – Patrick Sole
    Jan 15 at 23:26








  • 1




    $begingroup$
    @PatrickSole doesn’t it seem a little bad that every Abelian group is a (nonunitary) module over every rng? That’s certainly not the case for unitary modules.
    $endgroup$
    – rschwieb
    Jan 16 at 0:47










  • $begingroup$
    Things break down severely. This is more or less the reason why I insist that rings should have multiplicative neutral elements :-)
    $endgroup$
    – Jyrki Lahtonen
    Jan 17 at 22:54














4












4








4





$begingroup$


Are there any references on linear algebra (module theory) over non unital rings? What are the main differences with unital rings in that respect?










share|cite|improve this question









$endgroup$




Are there any references on linear algebra (module theory) over non unital rings? What are the main differences with unital rings in that respect?







ring-theory modules






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Jan 15 at 22:22









Patrick SolePatrick Sole

1177




1177












  • $begingroup$
    The main difference is that almost nothing works. The reason is simple: defining $rx=0$ for every $rin R$ and every $xin A$ defines an $R$-module structure on the abelian group $A$. Something better happens when you require that $RA=A$, in order that $A$ is a module.
    $endgroup$
    – egreg
    Jan 15 at 23:20












  • $begingroup$
    Can you elaborate on this simple reason?
    $endgroup$
    – Patrick Sole
    Jan 15 at 23:26








  • 1




    $begingroup$
    @PatrickSole doesn’t it seem a little bad that every Abelian group is a (nonunitary) module over every rng? That’s certainly not the case for unitary modules.
    $endgroup$
    – rschwieb
    Jan 16 at 0:47










  • $begingroup$
    Things break down severely. This is more or less the reason why I insist that rings should have multiplicative neutral elements :-)
    $endgroup$
    – Jyrki Lahtonen
    Jan 17 at 22:54


















  • $begingroup$
    The main difference is that almost nothing works. The reason is simple: defining $rx=0$ for every $rin R$ and every $xin A$ defines an $R$-module structure on the abelian group $A$. Something better happens when you require that $RA=A$, in order that $A$ is a module.
    $endgroup$
    – egreg
    Jan 15 at 23:20












  • $begingroup$
    Can you elaborate on this simple reason?
    $endgroup$
    – Patrick Sole
    Jan 15 at 23:26








  • 1




    $begingroup$
    @PatrickSole doesn’t it seem a little bad that every Abelian group is a (nonunitary) module over every rng? That’s certainly not the case for unitary modules.
    $endgroup$
    – rschwieb
    Jan 16 at 0:47










  • $begingroup$
    Things break down severely. This is more or less the reason why I insist that rings should have multiplicative neutral elements :-)
    $endgroup$
    – Jyrki Lahtonen
    Jan 17 at 22:54
















$begingroup$
The main difference is that almost nothing works. The reason is simple: defining $rx=0$ for every $rin R$ and every $xin A$ defines an $R$-module structure on the abelian group $A$. Something better happens when you require that $RA=A$, in order that $A$ is a module.
$endgroup$
– egreg
Jan 15 at 23:20






$begingroup$
The main difference is that almost nothing works. The reason is simple: defining $rx=0$ for every $rin R$ and every $xin A$ defines an $R$-module structure on the abelian group $A$. Something better happens when you require that $RA=A$, in order that $A$ is a module.
$endgroup$
– egreg
Jan 15 at 23:20














$begingroup$
Can you elaborate on this simple reason?
$endgroup$
– Patrick Sole
Jan 15 at 23:26






$begingroup$
Can you elaborate on this simple reason?
$endgroup$
– Patrick Sole
Jan 15 at 23:26






1




1




$begingroup$
@PatrickSole doesn’t it seem a little bad that every Abelian group is a (nonunitary) module over every rng? That’s certainly not the case for unitary modules.
$endgroup$
– rschwieb
Jan 16 at 0:47




$begingroup$
@PatrickSole doesn’t it seem a little bad that every Abelian group is a (nonunitary) module over every rng? That’s certainly not the case for unitary modules.
$endgroup$
– rschwieb
Jan 16 at 0:47












$begingroup$
Things break down severely. This is more or less the reason why I insist that rings should have multiplicative neutral elements :-)
$endgroup$
– Jyrki Lahtonen
Jan 17 at 22:54




$begingroup$
Things break down severely. This is more or less the reason why I insist that rings should have multiplicative neutral elements :-)
$endgroup$
– Jyrki Lahtonen
Jan 17 at 22:54










1 Answer
1






active

oldest

votes


















3












$begingroup$

Maybe not exactly what you're looking for, but these notes of Quillen say more about foundational matters regarding modules over non-unital rings than you probably thought possible!



He argues that the "correct" (I'm paraphrasing: he doesn't actually use that word) modules to consider are what he calls "firm modules".






share|cite|improve this answer









$endgroup$













    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%2f3075051%2fare-there-any-references-on-linear-algebra-module-theory-over-non-unital-rings%23new-answer', 'question_page');
    }
    );

    Post as a guest















    Required, but never shown

























    1 Answer
    1






    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3












    $begingroup$

    Maybe not exactly what you're looking for, but these notes of Quillen say more about foundational matters regarding modules over non-unital rings than you probably thought possible!



    He argues that the "correct" (I'm paraphrasing: he doesn't actually use that word) modules to consider are what he calls "firm modules".






    share|cite|improve this answer









    $endgroup$


















      3












      $begingroup$

      Maybe not exactly what you're looking for, but these notes of Quillen say more about foundational matters regarding modules over non-unital rings than you probably thought possible!



      He argues that the "correct" (I'm paraphrasing: he doesn't actually use that word) modules to consider are what he calls "firm modules".






      share|cite|improve this answer









      $endgroup$
















        3












        3








        3





        $begingroup$

        Maybe not exactly what you're looking for, but these notes of Quillen say more about foundational matters regarding modules over non-unital rings than you probably thought possible!



        He argues that the "correct" (I'm paraphrasing: he doesn't actually use that word) modules to consider are what he calls "firm modules".






        share|cite|improve this answer









        $endgroup$



        Maybe not exactly what you're looking for, but these notes of Quillen say more about foundational matters regarding modules over non-unital rings than you probably thought possible!



        He argues that the "correct" (I'm paraphrasing: he doesn't actually use that word) modules to consider are what he calls "firm modules".







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 16 at 10:50









        Jeremy RickardJeremy Rickard

        16.3k11643




        16.3k11643






























            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%2f3075051%2fare-there-any-references-on-linear-algebra-module-theory-over-non-unital-rings%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

            Mario Kart Wii

            The Binding of Isaac: Rebirth/Afterbirth

            What does “Dominus providebit” mean?