What does this symbol mean in commutative algebra?












0












$begingroup$


(Algebraic Geometry and commutative algebra - Bosch - page 16)



I could not find the symbol in the glossary at the end of the book. What does it mean ?



enter image description here



I cannot see it in my reference manual either (Commutative Algebra with a view towards algebraic geometry - Eisenbud)










share|cite|improve this question









$endgroup$








  • 2




    $begingroup$
    I suspect the symbol denotes a coproduct.
    $endgroup$
    – drhab
    Jan 12 at 9:42






  • 1




    $begingroup$
    As for the latex-symbol, see here.
    $endgroup$
    – Dietrich Burde
    Jan 12 at 9:48
















0












$begingroup$


(Algebraic Geometry and commutative algebra - Bosch - page 16)



I could not find the symbol in the glossary at the end of the book. What does it mean ?



enter image description here



I cannot see it in my reference manual either (Commutative Algebra with a view towards algebraic geometry - Eisenbud)










share|cite|improve this question









$endgroup$








  • 2




    $begingroup$
    I suspect the symbol denotes a coproduct.
    $endgroup$
    – drhab
    Jan 12 at 9:42






  • 1




    $begingroup$
    As for the latex-symbol, see here.
    $endgroup$
    – Dietrich Burde
    Jan 12 at 9:48














0












0








0





$begingroup$


(Algebraic Geometry and commutative algebra - Bosch - page 16)



I could not find the symbol in the glossary at the end of the book. What does it mean ?



enter image description here



I cannot see it in my reference manual either (Commutative Algebra with a view towards algebraic geometry - Eisenbud)










share|cite|improve this question









$endgroup$




(Algebraic Geometry and commutative algebra - Bosch - page 16)



I could not find the symbol in the glossary at the end of the book. What does it mean ?



enter image description here



I cannot see it in my reference manual either (Commutative Algebra with a view towards algebraic geometry - Eisenbud)







elementary-set-theory commutative-algebra






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Jan 12 at 9:35









user3203476user3203476

746613




746613








  • 2




    $begingroup$
    I suspect the symbol denotes a coproduct.
    $endgroup$
    – drhab
    Jan 12 at 9:42






  • 1




    $begingroup$
    As for the latex-symbol, see here.
    $endgroup$
    – Dietrich Burde
    Jan 12 at 9:48














  • 2




    $begingroup$
    I suspect the symbol denotes a coproduct.
    $endgroup$
    – drhab
    Jan 12 at 9:42






  • 1




    $begingroup$
    As for the latex-symbol, see here.
    $endgroup$
    – Dietrich Burde
    Jan 12 at 9:48








2




2




$begingroup$
I suspect the symbol denotes a coproduct.
$endgroup$
– drhab
Jan 12 at 9:42




$begingroup$
I suspect the symbol denotes a coproduct.
$endgroup$
– drhab
Jan 12 at 9:42




1




1




$begingroup$
As for the latex-symbol, see here.
$endgroup$
– Dietrich Burde
Jan 12 at 9:48




$begingroup$
As for the latex-symbol, see here.
$endgroup$
– Dietrich Burde
Jan 12 at 9:48










1 Answer
1






active

oldest

votes


















2












$begingroup$

Its the disjoint union from set theory. Each element of $text{Spec } R$ maps into a different set from the disjoint union.



In category theory this symbol can sometimes be a coproduct, but in this situation it’s not.



Added: Of course disjoint union is the coprduct in sets, but you hardly see all those rings/ $R$-modules and think “category of sets”. This tradition of confusing young scholars of scheme theory goes back, at least to Hartshorne’s book.






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%2f3070736%2fwhat-does-this-symbol-mean-in-commutative-algebra%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









    2












    $begingroup$

    Its the disjoint union from set theory. Each element of $text{Spec } R$ maps into a different set from the disjoint union.



    In category theory this symbol can sometimes be a coproduct, but in this situation it’s not.



    Added: Of course disjoint union is the coprduct in sets, but you hardly see all those rings/ $R$-modules and think “category of sets”. This tradition of confusing young scholars of scheme theory goes back, at least to Hartshorne’s book.






    share|cite|improve this answer











    $endgroup$


















      2












      $begingroup$

      Its the disjoint union from set theory. Each element of $text{Spec } R$ maps into a different set from the disjoint union.



      In category theory this symbol can sometimes be a coproduct, but in this situation it’s not.



      Added: Of course disjoint union is the coprduct in sets, but you hardly see all those rings/ $R$-modules and think “category of sets”. This tradition of confusing young scholars of scheme theory goes back, at least to Hartshorne’s book.






      share|cite|improve this answer











      $endgroup$
















        2












        2








        2





        $begingroup$

        Its the disjoint union from set theory. Each element of $text{Spec } R$ maps into a different set from the disjoint union.



        In category theory this symbol can sometimes be a coproduct, but in this situation it’s not.



        Added: Of course disjoint union is the coprduct in sets, but you hardly see all those rings/ $R$-modules and think “category of sets”. This tradition of confusing young scholars of scheme theory goes back, at least to Hartshorne’s book.






        share|cite|improve this answer











        $endgroup$



        Its the disjoint union from set theory. Each element of $text{Spec } R$ maps into a different set from the disjoint union.



        In category theory this symbol can sometimes be a coproduct, but in this situation it’s not.



        Added: Of course disjoint union is the coprduct in sets, but you hardly see all those rings/ $R$-modules and think “category of sets”. This tradition of confusing young scholars of scheme theory goes back, at least to Hartshorne’s book.







        share|cite|improve this answer














        share|cite|improve this answer



        share|cite|improve this answer








        edited Jan 12 at 9:53

























        answered Jan 12 at 9:45









        BenBen

        3,756616




        3,756616






























            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%2f3070736%2fwhat-does-this-symbol-mean-in-commutative-algebra%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

            'app-layout' is not a known element: how to share Component with different Modules

            android studio warns about leanback feature tag usage required on manifest while using Unity exported app?

            WPF add header to Image with URL pettitions [duplicate]