Dual of Schanuel's Lemma

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











up vote
2
down vote

favorite













Let $0 rightarrow M rightarrow E rightarrow K rightarrow 0$ and $0
rightarrow M rightarrow E' rightarrow K' rightarrow 0$ be short
exact sequences with $M$ a left $R$-module and $E, E'$ injective left
R-modules. Prove the dual version of Schanuel’s Lemma by showing that
E ⊕ K′ $cong$ E′ ⊕ K.




Two questions:



  1. What is the dual of Schanuel's Lemma precisely?

  2. How does "showing that E ⊕ K′ $cong$ E′ ⊕ K" succeed in proving the dual of Schanuel's Lemma?






share|cite|improve this question

















  • 1




    The dual of S's lemma is $Eoplus K'cong E'oplus K$.
    – Lord Shark the Unknown
    Jul 18 at 15:58










  • What does it mean for a E, E' to be "injective left R-modules"? I thought that only functions could be injective.
    – Tomislav Ostojich
    Jul 20 at 15:24










  • en.wikipedia.org/wiki/Injective_module
    – Lord Shark the Unknown
    Jul 20 at 15:25














up vote
2
down vote

favorite













Let $0 rightarrow M rightarrow E rightarrow K rightarrow 0$ and $0
rightarrow M rightarrow E' rightarrow K' rightarrow 0$ be short
exact sequences with $M$ a left $R$-module and $E, E'$ injective left
R-modules. Prove the dual version of Schanuel’s Lemma by showing that
E ⊕ K′ $cong$ E′ ⊕ K.




Two questions:



  1. What is the dual of Schanuel's Lemma precisely?

  2. How does "showing that E ⊕ K′ $cong$ E′ ⊕ K" succeed in proving the dual of Schanuel's Lemma?






share|cite|improve this question

















  • 1




    The dual of S's lemma is $Eoplus K'cong E'oplus K$.
    – Lord Shark the Unknown
    Jul 18 at 15:58










  • What does it mean for a E, E' to be "injective left R-modules"? I thought that only functions could be injective.
    – Tomislav Ostojich
    Jul 20 at 15:24










  • en.wikipedia.org/wiki/Injective_module
    – Lord Shark the Unknown
    Jul 20 at 15:25












up vote
2
down vote

favorite









up vote
2
down vote

favorite












Let $0 rightarrow M rightarrow E rightarrow K rightarrow 0$ and $0
rightarrow M rightarrow E' rightarrow K' rightarrow 0$ be short
exact sequences with $M$ a left $R$-module and $E, E'$ injective left
R-modules. Prove the dual version of Schanuel’s Lemma by showing that
E ⊕ K′ $cong$ E′ ⊕ K.




Two questions:



  1. What is the dual of Schanuel's Lemma precisely?

  2. How does "showing that E ⊕ K′ $cong$ E′ ⊕ K" succeed in proving the dual of Schanuel's Lemma?






share|cite|improve this question














Let $0 rightarrow M rightarrow E rightarrow K rightarrow 0$ and $0
rightarrow M rightarrow E' rightarrow K' rightarrow 0$ be short
exact sequences with $M$ a left $R$-module and $E, E'$ injective left
R-modules. Prove the dual version of Schanuel’s Lemma by showing that
E ⊕ K′ $cong$ E′ ⊕ K.




Two questions:



  1. What is the dual of Schanuel's Lemma precisely?

  2. How does "showing that E ⊕ K′ $cong$ E′ ⊕ K" succeed in proving the dual of Schanuel's Lemma?








share|cite|improve this question












share|cite|improve this question




share|cite|improve this question








edited Jul 18 at 15:37









Javi

2,1631725




2,1631725









asked Jul 18 at 15:34









Tomislav Ostojich

475313




475313







  • 1




    The dual of S's lemma is $Eoplus K'cong E'oplus K$.
    – Lord Shark the Unknown
    Jul 18 at 15:58










  • What does it mean for a E, E' to be "injective left R-modules"? I thought that only functions could be injective.
    – Tomislav Ostojich
    Jul 20 at 15:24










  • en.wikipedia.org/wiki/Injective_module
    – Lord Shark the Unknown
    Jul 20 at 15:25












  • 1




    The dual of S's lemma is $Eoplus K'cong E'oplus K$.
    – Lord Shark the Unknown
    Jul 18 at 15:58










  • What does it mean for a E, E' to be "injective left R-modules"? I thought that only functions could be injective.
    – Tomislav Ostojich
    Jul 20 at 15:24










  • en.wikipedia.org/wiki/Injective_module
    – Lord Shark the Unknown
    Jul 20 at 15:25







1




1




The dual of S's lemma is $Eoplus K'cong E'oplus K$.
– Lord Shark the Unknown
Jul 18 at 15:58




The dual of S's lemma is $Eoplus K'cong E'oplus K$.
– Lord Shark the Unknown
Jul 18 at 15:58












What does it mean for a E, E' to be "injective left R-modules"? I thought that only functions could be injective.
– Tomislav Ostojich
Jul 20 at 15:24




What does it mean for a E, E' to be "injective left R-modules"? I thought that only functions could be injective.
– Tomislav Ostojich
Jul 20 at 15:24












en.wikipedia.org/wiki/Injective_module
– Lord Shark the Unknown
Jul 20 at 15:25




en.wikipedia.org/wiki/Injective_module
– Lord Shark the Unknown
Jul 20 at 15:25















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',
convertImagesToLinks: true,
noModals: false,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
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%2f2855690%2fdual-of-schanuels-lemma%23new-answer', 'question_page');

);

Post as a guest



































active

oldest

votes













active

oldest

votes









active

oldest

votes






active

oldest

votes










 

draft saved


draft discarded


























 


draft saved


draft discarded














StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f2855690%2fdual-of-schanuels-lemma%23new-answer', 'question_page');

);

Post as a guest













































































Comments

Popular posts from this blog

Color the edges and diagonals of a regular polygon

Relationship between determinant of matrix and determinant of adjoint?

What is the equation of a 3D cone with generalised tilt?