van Kampen theorem for fundamental groupoid of $X$ relative to $A$












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$begingroup$


Let $X$ be a manifold with submanifold $A subseteq X$. Let $Pi_{1}(X,A)$ denote the homotopy classes of paths with endpoints lying in $A$. This is a Lie groupoid with set of objects $A$. For example, if $X$ is the upper hemisphere of a sphere and $A cong S^1$ is the equator, then $Pi_{1}(X,A) cong S^1$, and for any two objects there is a single morphism.



Question: Is there any theory developed for such groupoids? I'm looking for some kind of van Kampen theorem allowing me to express $Pi_{1}(X,A)$ in terms of $Pi_{1}(A)$ and $Pi_{1}(X setminus A)$.










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$endgroup$

















    2












    $begingroup$


    Let $X$ be a manifold with submanifold $A subseteq X$. Let $Pi_{1}(X,A)$ denote the homotopy classes of paths with endpoints lying in $A$. This is a Lie groupoid with set of objects $A$. For example, if $X$ is the upper hemisphere of a sphere and $A cong S^1$ is the equator, then $Pi_{1}(X,A) cong S^1$, and for any two objects there is a single morphism.



    Question: Is there any theory developed for such groupoids? I'm looking for some kind of van Kampen theorem allowing me to express $Pi_{1}(X,A)$ in terms of $Pi_{1}(A)$ and $Pi_{1}(X setminus A)$.










    share|cite|improve this question









    $endgroup$















      2












      2








      2





      $begingroup$


      Let $X$ be a manifold with submanifold $A subseteq X$. Let $Pi_{1}(X,A)$ denote the homotopy classes of paths with endpoints lying in $A$. This is a Lie groupoid with set of objects $A$. For example, if $X$ is the upper hemisphere of a sphere and $A cong S^1$ is the equator, then $Pi_{1}(X,A) cong S^1$, and for any two objects there is a single morphism.



      Question: Is there any theory developed for such groupoids? I'm looking for some kind of van Kampen theorem allowing me to express $Pi_{1}(X,A)$ in terms of $Pi_{1}(A)$ and $Pi_{1}(X setminus A)$.










      share|cite|improve this question









      $endgroup$




      Let $X$ be a manifold with submanifold $A subseteq X$. Let $Pi_{1}(X,A)$ denote the homotopy classes of paths with endpoints lying in $A$. This is a Lie groupoid with set of objects $A$. For example, if $X$ is the upper hemisphere of a sphere and $A cong S^1$ is the equator, then $Pi_{1}(X,A) cong S^1$, and for any two objects there is a single morphism.



      Question: Is there any theory developed for such groupoids? I'm looking for some kind of van Kampen theorem allowing me to express $Pi_{1}(X,A)$ in terms of $Pi_{1}(A)$ and $Pi_{1}(X setminus A)$.







      algebraic-topology fundamental-groups groupoids






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      asked Jul 1 '15 at 8:04









      unknownymousunknownymous

      601310




      601310






















          1 Answer
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          $begingroup$

          Yes sure!



          There is the book by R. Brown, "Topology and Groupoids", which treats exactly this: http://groupoids.org.uk/topgpds.html



          Look also here: http://groupoids.org.uk/nonab-a-t.html



          On the nlab (if you didn't know the site, take a look!) there are also these articles that you may find interesting!



          http://ncatlab.org/nlab/show/van+Kampen+theorem



          http://ncatlab.org/nlab/show/higher+homotopy+van+Kampen+theorem






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            See also my answer mathoverflow.net/questions/39818/…, and presentations on my my preprint page pages.bangor.ac.uk/~mas010/brownpr.html .
            $endgroup$
            – Ronnie Brown
            Jul 1 '15 at 21:23











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          1 Answer
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          active

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          active

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          active

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          $begingroup$

          Yes sure!



          There is the book by R. Brown, "Topology and Groupoids", which treats exactly this: http://groupoids.org.uk/topgpds.html



          Look also here: http://groupoids.org.uk/nonab-a-t.html



          On the nlab (if you didn't know the site, take a look!) there are also these articles that you may find interesting!



          http://ncatlab.org/nlab/show/van+Kampen+theorem



          http://ncatlab.org/nlab/show/higher+homotopy+van+Kampen+theorem






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            See also my answer mathoverflow.net/questions/39818/…, and presentations on my my preprint page pages.bangor.ac.uk/~mas010/brownpr.html .
            $endgroup$
            – Ronnie Brown
            Jul 1 '15 at 21:23
















          1












          $begingroup$

          Yes sure!



          There is the book by R. Brown, "Topology and Groupoids", which treats exactly this: http://groupoids.org.uk/topgpds.html



          Look also here: http://groupoids.org.uk/nonab-a-t.html



          On the nlab (if you didn't know the site, take a look!) there are also these articles that you may find interesting!



          http://ncatlab.org/nlab/show/van+Kampen+theorem



          http://ncatlab.org/nlab/show/higher+homotopy+van+Kampen+theorem






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            See also my answer mathoverflow.net/questions/39818/…, and presentations on my my preprint page pages.bangor.ac.uk/~mas010/brownpr.html .
            $endgroup$
            – Ronnie Brown
            Jul 1 '15 at 21:23














          1












          1








          1





          $begingroup$

          Yes sure!



          There is the book by R. Brown, "Topology and Groupoids", which treats exactly this: http://groupoids.org.uk/topgpds.html



          Look also here: http://groupoids.org.uk/nonab-a-t.html



          On the nlab (if you didn't know the site, take a look!) there are also these articles that you may find interesting!



          http://ncatlab.org/nlab/show/van+Kampen+theorem



          http://ncatlab.org/nlab/show/higher+homotopy+van+Kampen+theorem






          share|cite|improve this answer











          $endgroup$



          Yes sure!



          There is the book by R. Brown, "Topology and Groupoids", which treats exactly this: http://groupoids.org.uk/topgpds.html



          Look also here: http://groupoids.org.uk/nonab-a-t.html



          On the nlab (if you didn't know the site, take a look!) there are also these articles that you may find interesting!



          http://ncatlab.org/nlab/show/van+Kampen+theorem



          http://ncatlab.org/nlab/show/higher+homotopy+van+Kampen+theorem







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Jan 13 at 11:36









          Ronnie Brown

          12.1k12939




          12.1k12939










          answered Jul 1 '15 at 9:47









          geodudegeodude

          4,1161343




          4,1161343












          • $begingroup$
            See also my answer mathoverflow.net/questions/39818/…, and presentations on my my preprint page pages.bangor.ac.uk/~mas010/brownpr.html .
            $endgroup$
            – Ronnie Brown
            Jul 1 '15 at 21:23


















          • $begingroup$
            See also my answer mathoverflow.net/questions/39818/…, and presentations on my my preprint page pages.bangor.ac.uk/~mas010/brownpr.html .
            $endgroup$
            – Ronnie Brown
            Jul 1 '15 at 21:23
















          $begingroup$
          See also my answer mathoverflow.net/questions/39818/…, and presentations on my my preprint page pages.bangor.ac.uk/~mas010/brownpr.html .
          $endgroup$
          – Ronnie Brown
          Jul 1 '15 at 21:23




          $begingroup$
          See also my answer mathoverflow.net/questions/39818/…, and presentations on my my preprint page pages.bangor.ac.uk/~mas010/brownpr.html .
          $endgroup$
          – Ronnie Brown
          Jul 1 '15 at 21:23


















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