“Cyclic” continuum

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On p. 221 of http://topology.auburn.edu/tp/reprints/v08/tp08113.pdf, I found the following definition:



"A curve is said to be cyclic if its first Čech cohomology group with integer coefficients does not vanish".



Here, a curve means a homogeneous metric continuum of dimension 1.



Can someone explain this definition in different, more elementary, terms, and give some examples to illustrate the meaning?










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    up vote
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    On p. 221 of http://topology.auburn.edu/tp/reprints/v08/tp08113.pdf, I found the following definition:



    "A curve is said to be cyclic if its first Čech cohomology group with integer coefficients does not vanish".



    Here, a curve means a homogeneous metric continuum of dimension 1.



    Can someone explain this definition in different, more elementary, terms, and give some examples to illustrate the meaning?










    share|cite|improve this question

























      up vote
      6
      down vote

      favorite
      3









      up vote
      6
      down vote

      favorite
      3






      3





      On p. 221 of http://topology.auburn.edu/tp/reprints/v08/tp08113.pdf, I found the following definition:



      "A curve is said to be cyclic if its first Čech cohomology group with integer coefficients does not vanish".



      Here, a curve means a homogeneous metric continuum of dimension 1.



      Can someone explain this definition in different, more elementary, terms, and give some examples to illustrate the meaning?










      share|cite|improve this question















      On p. 221 of http://topology.auburn.edu/tp/reprints/v08/tp08113.pdf, I found the following definition:



      "A curve is said to be cyclic if its first Čech cohomology group with integer coefficients does not vanish".



      Here, a curve means a homogeneous metric continuum of dimension 1.



      Can someone explain this definition in different, more elementary, terms, and give some examples to illustrate the meaning?







      gn.general-topology cohomology definitions






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      edited Sep 30 at 22:27









      Amir Sagiv

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      asked Sep 30 at 21:09







      user129590



























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          Perhaps the first Čech cohomology group with integer coefficients may seem not elementary. Then use the characterization of it as the first Borsuk's cohomotopy group (or it appears as the Brushlinsky's group in the well-known text on Homotopy Theory by Hu). This group's elements are simply the homotopy classes of mappings into $ mathbb S^1.$ Space $ S^1 $ is a topological group, it induces the group structure on the homotopy classes.






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            Perhaps the first Čech cohomology group with integer coefficients may seem not elementary. Then use the characterization of it as the first Borsuk's cohomotopy group (or it appears as the Brushlinsky's group in the well-known text on Homotopy Theory by Hu). This group's elements are simply the homotopy classes of mappings into $ mathbb S^1.$ Space $ S^1 $ is a topological group, it induces the group structure on the homotopy classes.






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              5
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              Perhaps the first Čech cohomology group with integer coefficients may seem not elementary. Then use the characterization of it as the first Borsuk's cohomotopy group (or it appears as the Brushlinsky's group in the well-known text on Homotopy Theory by Hu). This group's elements are simply the homotopy classes of mappings into $ mathbb S^1.$ Space $ S^1 $ is a topological group, it induces the group structure on the homotopy classes.






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                up vote
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                up vote
                5
                down vote









                Perhaps the first Čech cohomology group with integer coefficients may seem not elementary. Then use the characterization of it as the first Borsuk's cohomotopy group (or it appears as the Brushlinsky's group in the well-known text on Homotopy Theory by Hu). This group's elements are simply the homotopy classes of mappings into $ mathbb S^1.$ Space $ S^1 $ is a topological group, it induces the group structure on the homotopy classes.






                share|cite|improve this answer












                Perhaps the first Čech cohomology group with integer coefficients may seem not elementary. Then use the characterization of it as the first Borsuk's cohomotopy group (or it appears as the Brushlinsky's group in the well-known text on Homotopy Theory by Hu). This group's elements are simply the homotopy classes of mappings into $ mathbb S^1.$ Space $ S^1 $ is a topological group, it induces the group structure on the homotopy classes.







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                answered Sep 30 at 21:22









                Wlod AA

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