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Universal covering space of the real projective line?

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Universal covering space of the real projective line?



Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm US/Eastern)universal abelian covering spaceUniversal covering space via fiber productUniversal covering space of CW complex has CW complex structureUniversal covering space of wedge sumAbout the definition of universal covering spaceAlgorithms for finding covering spaces of a given spaceCan the real projective plane be considered as a covering space of a closed disk?Why the plane isn't universal covering space of $mathbb RP^2$?Universal covering space for the following topological spaces.Constructing a universal covering space












5












$begingroup$


I´m thinking about universal covering spaces. I´ve seen a lot of examples and authors ever say "the sphere $S^n$ is the universal covering space of the $n$-dimensional projective space $mathbb{R}P^n$ for $n geq 1$.



So my question is: and what about the real projective line $mathbb{R}P^1$? Has it universal covering space?



Thanks!










share|cite|improve this question









$endgroup$

















    5












    $begingroup$


    I´m thinking about universal covering spaces. I´ve seen a lot of examples and authors ever say "the sphere $S^n$ is the universal covering space of the $n$-dimensional projective space $mathbb{R}P^n$ for $n geq 1$.



    So my question is: and what about the real projective line $mathbb{R}P^1$? Has it universal covering space?



    Thanks!










    share|cite|improve this question









    $endgroup$















      5












      5








      5





      $begingroup$


      I´m thinking about universal covering spaces. I´ve seen a lot of examples and authors ever say "the sphere $S^n$ is the universal covering space of the $n$-dimensional projective space $mathbb{R}P^n$ for $n geq 1$.



      So my question is: and what about the real projective line $mathbb{R}P^1$? Has it universal covering space?



      Thanks!










      share|cite|improve this question









      $endgroup$




      I´m thinking about universal covering spaces. I´ve seen a lot of examples and authors ever say "the sphere $S^n$ is the universal covering space of the $n$-dimensional projective space $mathbb{R}P^n$ for $n geq 1$.



      So my question is: and what about the real projective line $mathbb{R}P^1$? Has it universal covering space?



      Thanks!







      algebraic-topology covering-spaces






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked 6 hours ago









      user183002user183002

      584




      584






















          2 Answers
          2






          active

          oldest

          votes


















          4












          $begingroup$

          $mathbb{R}P^1$ is homeomorphic to $mathbb{S}^1$. To see this, first note that more generaly $mathbb{R}P^nsimeqmathbb{S}^n/_{pm id}$ and in the case $n=1$ you have $ mathbb{S}^1/_{pm id}simeq mathbb{S}^1$ (just factorize the map $zmapsto z^2$).



          From here you can conclude.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Sure! I had the homeomorphism but I missed it! Lol. Thanks! :D
            $endgroup$
            – user183002
            5 hours ago



















          3












          $begingroup$

          The real projective line is just a circle, so the universal covering space is the real line.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I don´t agree. Even it´s not a circumference. It´s a quotient of a circumference, yeah?
            $endgroup$
            – user183002
            6 hours ago






          • 1




            $begingroup$
            @user A cheap way to see it is that the unique closed one dimensional manifold is a circle. There's nothing else it can be.
            $endgroup$
            – Matt Samuel
            6 hours ago










          • $begingroup$
            Important to note is that it isn’t the universal cover.
            $endgroup$
            – Connor Malin
            4 hours ago










          • $begingroup$
            What I mean is that $S^1 rightarrow mathbb{R}P^1$ is a covering space, but not a universal one.
            $endgroup$
            – Connor Malin
            3 hours ago








          • 1




            $begingroup$
            @Connor I agree. Note my answer says the real line is the universal cover.
            $endgroup$
            – Matt Samuel
            3 hours ago












          Your Answer








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          2 Answers
          2






          active

          oldest

          votes








          2 Answers
          2






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          4












          $begingroup$

          $mathbb{R}P^1$ is homeomorphic to $mathbb{S}^1$. To see this, first note that more generaly $mathbb{R}P^nsimeqmathbb{S}^n/_{pm id}$ and in the case $n=1$ you have $ mathbb{S}^1/_{pm id}simeq mathbb{S}^1$ (just factorize the map $zmapsto z^2$).



          From here you can conclude.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Sure! I had the homeomorphism but I missed it! Lol. Thanks! :D
            $endgroup$
            – user183002
            5 hours ago
















          4












          $begingroup$

          $mathbb{R}P^1$ is homeomorphic to $mathbb{S}^1$. To see this, first note that more generaly $mathbb{R}P^nsimeqmathbb{S}^n/_{pm id}$ and in the case $n=1$ you have $ mathbb{S}^1/_{pm id}simeq mathbb{S}^1$ (just factorize the map $zmapsto z^2$).



          From here you can conclude.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Sure! I had the homeomorphism but I missed it! Lol. Thanks! :D
            $endgroup$
            – user183002
            5 hours ago














          4












          4








          4





          $begingroup$

          $mathbb{R}P^1$ is homeomorphic to $mathbb{S}^1$. To see this, first note that more generaly $mathbb{R}P^nsimeqmathbb{S}^n/_{pm id}$ and in the case $n=1$ you have $ mathbb{S}^1/_{pm id}simeq mathbb{S}^1$ (just factorize the map $zmapsto z^2$).



          From here you can conclude.






          share|cite|improve this answer











          $endgroup$



          $mathbb{R}P^1$ is homeomorphic to $mathbb{S}^1$. To see this, first note that more generaly $mathbb{R}P^nsimeqmathbb{S}^n/_{pm id}$ and in the case $n=1$ you have $ mathbb{S}^1/_{pm id}simeq mathbb{S}^1$ (just factorize the map $zmapsto z^2$).



          From here you can conclude.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited 2 hours ago









          Servaes

          30.9k342101




          30.9k342101










          answered 6 hours ago









          AdamAdam

          1037




          1037












          • $begingroup$
            Sure! I had the homeomorphism but I missed it! Lol. Thanks! :D
            $endgroup$
            – user183002
            5 hours ago


















          • $begingroup$
            Sure! I had the homeomorphism but I missed it! Lol. Thanks! :D
            $endgroup$
            – user183002
            5 hours ago
















          $begingroup$
          Sure! I had the homeomorphism but I missed it! Lol. Thanks! :D
          $endgroup$
          – user183002
          5 hours ago




          $begingroup$
          Sure! I had the homeomorphism but I missed it! Lol. Thanks! :D
          $endgroup$
          – user183002
          5 hours ago











          3












          $begingroup$

          The real projective line is just a circle, so the universal covering space is the real line.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I don´t agree. Even it´s not a circumference. It´s a quotient of a circumference, yeah?
            $endgroup$
            – user183002
            6 hours ago






          • 1




            $begingroup$
            @user A cheap way to see it is that the unique closed one dimensional manifold is a circle. There's nothing else it can be.
            $endgroup$
            – Matt Samuel
            6 hours ago










          • $begingroup$
            Important to note is that it isn’t the universal cover.
            $endgroup$
            – Connor Malin
            4 hours ago










          • $begingroup$
            What I mean is that $S^1 rightarrow mathbb{R}P^1$ is a covering space, but not a universal one.
            $endgroup$
            – Connor Malin
            3 hours ago








          • 1




            $begingroup$
            @Connor I agree. Note my answer says the real line is the universal cover.
            $endgroup$
            – Matt Samuel
            3 hours ago
















          3












          $begingroup$

          The real projective line is just a circle, so the universal covering space is the real line.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I don´t agree. Even it´s not a circumference. It´s a quotient of a circumference, yeah?
            $endgroup$
            – user183002
            6 hours ago






          • 1




            $begingroup$
            @user A cheap way to see it is that the unique closed one dimensional manifold is a circle. There's nothing else it can be.
            $endgroup$
            – Matt Samuel
            6 hours ago










          • $begingroup$
            Important to note is that it isn’t the universal cover.
            $endgroup$
            – Connor Malin
            4 hours ago










          • $begingroup$
            What I mean is that $S^1 rightarrow mathbb{R}P^1$ is a covering space, but not a universal one.
            $endgroup$
            – Connor Malin
            3 hours ago








          • 1




            $begingroup$
            @Connor I agree. Note my answer says the real line is the universal cover.
            $endgroup$
            – Matt Samuel
            3 hours ago














          3












          3








          3





          $begingroup$

          The real projective line is just a circle, so the universal covering space is the real line.






          share|cite|improve this answer









          $endgroup$



          The real projective line is just a circle, so the universal covering space is the real line.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered 6 hours ago









          Matt SamuelMatt Samuel

          39.4k63870




          39.4k63870












          • $begingroup$
            I don´t agree. Even it´s not a circumference. It´s a quotient of a circumference, yeah?
            $endgroup$
            – user183002
            6 hours ago






          • 1




            $begingroup$
            @user A cheap way to see it is that the unique closed one dimensional manifold is a circle. There's nothing else it can be.
            $endgroup$
            – Matt Samuel
            6 hours ago










          • $begingroup$
            Important to note is that it isn’t the universal cover.
            $endgroup$
            – Connor Malin
            4 hours ago










          • $begingroup$
            What I mean is that $S^1 rightarrow mathbb{R}P^1$ is a covering space, but not a universal one.
            $endgroup$
            – Connor Malin
            3 hours ago








          • 1




            $begingroup$
            @Connor I agree. Note my answer says the real line is the universal cover.
            $endgroup$
            – Matt Samuel
            3 hours ago


















          • $begingroup$
            I don´t agree. Even it´s not a circumference. It´s a quotient of a circumference, yeah?
            $endgroup$
            – user183002
            6 hours ago






          • 1




            $begingroup$
            @user A cheap way to see it is that the unique closed one dimensional manifold is a circle. There's nothing else it can be.
            $endgroup$
            – Matt Samuel
            6 hours ago










          • $begingroup$
            Important to note is that it isn’t the universal cover.
            $endgroup$
            – Connor Malin
            4 hours ago










          • $begingroup$
            What I mean is that $S^1 rightarrow mathbb{R}P^1$ is a covering space, but not a universal one.
            $endgroup$
            – Connor Malin
            3 hours ago








          • 1




            $begingroup$
            @Connor I agree. Note my answer says the real line is the universal cover.
            $endgroup$
            – Matt Samuel
            3 hours ago
















          $begingroup$
          I don´t agree. Even it´s not a circumference. It´s a quotient of a circumference, yeah?
          $endgroup$
          – user183002
          6 hours ago




          $begingroup$
          I don´t agree. Even it´s not a circumference. It´s a quotient of a circumference, yeah?
          $endgroup$
          – user183002
          6 hours ago




          1




          1




          $begingroup$
          @user A cheap way to see it is that the unique closed one dimensional manifold is a circle. There's nothing else it can be.
          $endgroup$
          – Matt Samuel
          6 hours ago




          $begingroup$
          @user A cheap way to see it is that the unique closed one dimensional manifold is a circle. There's nothing else it can be.
          $endgroup$
          – Matt Samuel
          6 hours ago












          $begingroup$
          Important to note is that it isn’t the universal cover.
          $endgroup$
          – Connor Malin
          4 hours ago




          $begingroup$
          Important to note is that it isn’t the universal cover.
          $endgroup$
          – Connor Malin
          4 hours ago












          $begingroup$
          What I mean is that $S^1 rightarrow mathbb{R}P^1$ is a covering space, but not a universal one.
          $endgroup$
          – Connor Malin
          3 hours ago






          $begingroup$
          What I mean is that $S^1 rightarrow mathbb{R}P^1$ is a covering space, but not a universal one.
          $endgroup$
          – Connor Malin
          3 hours ago






          1




          1




          $begingroup$
          @Connor I agree. Note my answer says the real line is the universal cover.
          $endgroup$
          – Matt Samuel
          3 hours ago




          $begingroup$
          @Connor I agree. Note my answer says the real line is the universal cover.
          $endgroup$
          – Matt Samuel
          3 hours ago


















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