De Rham cohomology of $mathbb{RP^n}$











up vote
1
down vote

favorite












I have to calculate the De Rham cohomology of $mathbb{RP^n}$ using the Mayer-Vietoris sequence.



I first started by considering $mathbb{RP^n}=S^n/sim $ where $sim$ is the antipodal identification. Then I wrote $mathbb{RP^n}$ as the union of the sets



$U=S^n- {(0,...0,1)}$



and



$V=S^n- {(1,0,...,0)}$



But when I start using Mayer-Vietoris sequence I don't know how to proceed. Do I need to calculate it by induction on the order of the cohomology? Have you any hints or references in which it is solved?



Thank you.










share|cite|improve this question




















  • 1




    Well you should try to first figure out the cohomology of $U$, $V$, and $U cap V$. Then you should try to figure out what the induced maps on cohomology are. Then you can hope that can exactness will help to figure out the cohomology groups.
    – DKS
    Nov 16 at 18:20










  • @DKS These are precisely the steps I can't do. Is there a place where it's explained?
    – Phi_24
    Nov 17 at 13:28















up vote
1
down vote

favorite












I have to calculate the De Rham cohomology of $mathbb{RP^n}$ using the Mayer-Vietoris sequence.



I first started by considering $mathbb{RP^n}=S^n/sim $ where $sim$ is the antipodal identification. Then I wrote $mathbb{RP^n}$ as the union of the sets



$U=S^n- {(0,...0,1)}$



and



$V=S^n- {(1,0,...,0)}$



But when I start using Mayer-Vietoris sequence I don't know how to proceed. Do I need to calculate it by induction on the order of the cohomology? Have you any hints or references in which it is solved?



Thank you.










share|cite|improve this question




















  • 1




    Well you should try to first figure out the cohomology of $U$, $V$, and $U cap V$. Then you should try to figure out what the induced maps on cohomology are. Then you can hope that can exactness will help to figure out the cohomology groups.
    – DKS
    Nov 16 at 18:20










  • @DKS These are precisely the steps I can't do. Is there a place where it's explained?
    – Phi_24
    Nov 17 at 13:28













up vote
1
down vote

favorite









up vote
1
down vote

favorite











I have to calculate the De Rham cohomology of $mathbb{RP^n}$ using the Mayer-Vietoris sequence.



I first started by considering $mathbb{RP^n}=S^n/sim $ where $sim$ is the antipodal identification. Then I wrote $mathbb{RP^n}$ as the union of the sets



$U=S^n- {(0,...0,1)}$



and



$V=S^n- {(1,0,...,0)}$



But when I start using Mayer-Vietoris sequence I don't know how to proceed. Do I need to calculate it by induction on the order of the cohomology? Have you any hints or references in which it is solved?



Thank you.










share|cite|improve this question















I have to calculate the De Rham cohomology of $mathbb{RP^n}$ using the Mayer-Vietoris sequence.



I first started by considering $mathbb{RP^n}=S^n/sim $ where $sim$ is the antipodal identification. Then I wrote $mathbb{RP^n}$ as the union of the sets



$U=S^n- {(0,...0,1)}$



and



$V=S^n- {(1,0,...,0)}$



But when I start using Mayer-Vietoris sequence I don't know how to proceed. Do I need to calculate it by induction on the order of the cohomology? Have you any hints or references in which it is solved?



Thank you.







algebraic-topology projective-space de-rham-cohomology






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Nov 16 at 19:38









KReiser

9,08711335




9,08711335










asked Nov 16 at 17:44









Phi_24

1248




1248








  • 1




    Well you should try to first figure out the cohomology of $U$, $V$, and $U cap V$. Then you should try to figure out what the induced maps on cohomology are. Then you can hope that can exactness will help to figure out the cohomology groups.
    – DKS
    Nov 16 at 18:20










  • @DKS These are precisely the steps I can't do. Is there a place where it's explained?
    – Phi_24
    Nov 17 at 13:28














  • 1




    Well you should try to first figure out the cohomology of $U$, $V$, and $U cap V$. Then you should try to figure out what the induced maps on cohomology are. Then you can hope that can exactness will help to figure out the cohomology groups.
    – DKS
    Nov 16 at 18:20










  • @DKS These are precisely the steps I can't do. Is there a place where it's explained?
    – Phi_24
    Nov 17 at 13:28








1




1




Well you should try to first figure out the cohomology of $U$, $V$, and $U cap V$. Then you should try to figure out what the induced maps on cohomology are. Then you can hope that can exactness will help to figure out the cohomology groups.
– DKS
Nov 16 at 18:20




Well you should try to first figure out the cohomology of $U$, $V$, and $U cap V$. Then you should try to figure out what the induced maps on cohomology are. Then you can hope that can exactness will help to figure out the cohomology groups.
– DKS
Nov 16 at 18:20












@DKS These are precisely the steps I can't do. Is there a place where it's explained?
– Phi_24
Nov 17 at 13:28




@DKS These are precisely the steps I can't do. Is there a place where it's explained?
– Phi_24
Nov 17 at 13:28















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: 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%2f3001431%2fde-rham-cohomology-of-mathbbrpn%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown






























active

oldest

votes













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.





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%2f3001431%2fde-rham-cohomology-of-mathbbrpn%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

Plaza Victoria

Puebla de Zaragoza

Musa