Question regarding the image of the unity $e$ of the ring $R$.












1














I was reading Ring Homomorphism .



$phi : R to R'$ is a ring homomorphism and $e , e'$ are the unities of $R $ and $R'$ respectively.



I understood that $phi (e) $ may not be unity of $R'$.



I think the following statements are true.



( 1 ) $phi (e) $ is always unity of $phi (R) $ .



(2) If $phi $ is on to then $phi (e) = e'$



(3) If $phi $ is non trivial and $R'$ is a field then $phi (e) = e'$.



Can someone check if there is any mistake in my understanding?










share|cite|improve this question
























  • $phi (R) $ is a ring with unity $phi (e)$@BadamBaplan
    – cmi
    Dec 11 '18 at 4:47












  • Did you understand or not?@BadamBaplan
    – cmi
    Dec 11 '18 at 4:56










  • $phi (R)$ is always a subring and $phi(e)$ may not be the unity of $R'$. Proof or the first statement is very easy and see this math.stackexchange.com/questions/179842/… for the scond one.@BadamBaplan
    – cmi
    Dec 11 '18 at 5:08










  • No no unity@BadamBaplan
    – cmi
    Dec 11 '18 at 5:09










  • Yes $phi(R)$ is always a ring contained in $R$ with unit $phi(e)$. You seem to understand all of these things fine, so I'm not sure what you're looking for. Usually we require 'subrings' to contain the unity of their parent rings. I was just pointing out the connection that $phi(R)$ is a subring in that sense iff $phi(e) = e'$
    – Badam Baplan
    Dec 11 '18 at 5:31
















1














I was reading Ring Homomorphism .



$phi : R to R'$ is a ring homomorphism and $e , e'$ are the unities of $R $ and $R'$ respectively.



I understood that $phi (e) $ may not be unity of $R'$.



I think the following statements are true.



( 1 ) $phi (e) $ is always unity of $phi (R) $ .



(2) If $phi $ is on to then $phi (e) = e'$



(3) If $phi $ is non trivial and $R'$ is a field then $phi (e) = e'$.



Can someone check if there is any mistake in my understanding?










share|cite|improve this question
























  • $phi (R) $ is a ring with unity $phi (e)$@BadamBaplan
    – cmi
    Dec 11 '18 at 4:47












  • Did you understand or not?@BadamBaplan
    – cmi
    Dec 11 '18 at 4:56










  • $phi (R)$ is always a subring and $phi(e)$ may not be the unity of $R'$. Proof or the first statement is very easy and see this math.stackexchange.com/questions/179842/… for the scond one.@BadamBaplan
    – cmi
    Dec 11 '18 at 5:08










  • No no unity@BadamBaplan
    – cmi
    Dec 11 '18 at 5:09










  • Yes $phi(R)$ is always a ring contained in $R$ with unit $phi(e)$. You seem to understand all of these things fine, so I'm not sure what you're looking for. Usually we require 'subrings' to contain the unity of their parent rings. I was just pointing out the connection that $phi(R)$ is a subring in that sense iff $phi(e) = e'$
    – Badam Baplan
    Dec 11 '18 at 5:31














1












1








1


2





I was reading Ring Homomorphism .



$phi : R to R'$ is a ring homomorphism and $e , e'$ are the unities of $R $ and $R'$ respectively.



I understood that $phi (e) $ may not be unity of $R'$.



I think the following statements are true.



( 1 ) $phi (e) $ is always unity of $phi (R) $ .



(2) If $phi $ is on to then $phi (e) = e'$



(3) If $phi $ is non trivial and $R'$ is a field then $phi (e) = e'$.



Can someone check if there is any mistake in my understanding?










share|cite|improve this question















I was reading Ring Homomorphism .



$phi : R to R'$ is a ring homomorphism and $e , e'$ are the unities of $R $ and $R'$ respectively.



I understood that $phi (e) $ may not be unity of $R'$.



I think the following statements are true.



( 1 ) $phi (e) $ is always unity of $phi (R) $ .



(2) If $phi $ is on to then $phi (e) = e'$



(3) If $phi $ is non trivial and $R'$ is a field then $phi (e) = e'$.



Can someone check if there is any mistake in my understanding?







abstract-algebra ring-theory field-theory






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 11 '18 at 4:41

























asked Dec 11 '18 at 4:24









cmi

1,003212




1,003212












  • $phi (R) $ is a ring with unity $phi (e)$@BadamBaplan
    – cmi
    Dec 11 '18 at 4:47












  • Did you understand or not?@BadamBaplan
    – cmi
    Dec 11 '18 at 4:56










  • $phi (R)$ is always a subring and $phi(e)$ may not be the unity of $R'$. Proof or the first statement is very easy and see this math.stackexchange.com/questions/179842/… for the scond one.@BadamBaplan
    – cmi
    Dec 11 '18 at 5:08










  • No no unity@BadamBaplan
    – cmi
    Dec 11 '18 at 5:09










  • Yes $phi(R)$ is always a ring contained in $R$ with unit $phi(e)$. You seem to understand all of these things fine, so I'm not sure what you're looking for. Usually we require 'subrings' to contain the unity of their parent rings. I was just pointing out the connection that $phi(R)$ is a subring in that sense iff $phi(e) = e'$
    – Badam Baplan
    Dec 11 '18 at 5:31


















  • $phi (R) $ is a ring with unity $phi (e)$@BadamBaplan
    – cmi
    Dec 11 '18 at 4:47












  • Did you understand or not?@BadamBaplan
    – cmi
    Dec 11 '18 at 4:56










  • $phi (R)$ is always a subring and $phi(e)$ may not be the unity of $R'$. Proof or the first statement is very easy and see this math.stackexchange.com/questions/179842/… for the scond one.@BadamBaplan
    – cmi
    Dec 11 '18 at 5:08










  • No no unity@BadamBaplan
    – cmi
    Dec 11 '18 at 5:09










  • Yes $phi(R)$ is always a ring contained in $R$ with unit $phi(e)$. You seem to understand all of these things fine, so I'm not sure what you're looking for. Usually we require 'subrings' to contain the unity of their parent rings. I was just pointing out the connection that $phi(R)$ is a subring in that sense iff $phi(e) = e'$
    – Badam Baplan
    Dec 11 '18 at 5:31
















$phi (R) $ is a ring with unity $phi (e)$@BadamBaplan
– cmi
Dec 11 '18 at 4:47






$phi (R) $ is a ring with unity $phi (e)$@BadamBaplan
– cmi
Dec 11 '18 at 4:47














Did you understand or not?@BadamBaplan
– cmi
Dec 11 '18 at 4:56




Did you understand or not?@BadamBaplan
– cmi
Dec 11 '18 at 4:56












$phi (R)$ is always a subring and $phi(e)$ may not be the unity of $R'$. Proof or the first statement is very easy and see this math.stackexchange.com/questions/179842/… for the scond one.@BadamBaplan
– cmi
Dec 11 '18 at 5:08




$phi (R)$ is always a subring and $phi(e)$ may not be the unity of $R'$. Proof or the first statement is very easy and see this math.stackexchange.com/questions/179842/… for the scond one.@BadamBaplan
– cmi
Dec 11 '18 at 5:08












No no unity@BadamBaplan
– cmi
Dec 11 '18 at 5:09




No no unity@BadamBaplan
– cmi
Dec 11 '18 at 5:09












Yes $phi(R)$ is always a ring contained in $R$ with unit $phi(e)$. You seem to understand all of these things fine, so I'm not sure what you're looking for. Usually we require 'subrings' to contain the unity of their parent rings. I was just pointing out the connection that $phi(R)$ is a subring in that sense iff $phi(e) = e'$
– Badam Baplan
Dec 11 '18 at 5:31




Yes $phi(R)$ is always a ring contained in $R$ with unit $phi(e)$. You seem to understand all of these things fine, so I'm not sure what you're looking for. Usually we require 'subrings' to contain the unity of their parent rings. I was just pointing out the connection that $phi(R)$ is a subring in that sense iff $phi(e) = e'$
– Badam Baplan
Dec 11 '18 at 5:31










1 Answer
1






active

oldest

votes


















1














Yes your 3 statements are true and easy to prove ,I assume you can prove them .






share|cite|improve this answer





















    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%2f3034882%2fquestion-regarding-the-image-of-the-unity-e-of-the-ring-r%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









    1














    Yes your 3 statements are true and easy to prove ,I assume you can prove them .






    share|cite|improve this answer


























      1














      Yes your 3 statements are true and easy to prove ,I assume you can prove them .






      share|cite|improve this answer
























        1












        1








        1






        Yes your 3 statements are true and easy to prove ,I assume you can prove them .






        share|cite|improve this answer












        Yes your 3 statements are true and easy to prove ,I assume you can prove them .







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 11 '18 at 5:24









        StuartMN

        1,406410




        1,406410






























            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.





            Some of your past answers have not been well-received, and you're in danger of being blocked from answering.


            Please pay close attention to the following guidance:


            • 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.


            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%2f3034882%2fquestion-regarding-the-image-of-the-unity-e-of-the-ring-r%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

            Karlovacs län

            Cabo Verde

            Fundamental Group of Connected Sum of two $3$-manifolds