Smooth bijection and tangent spaces












1












$begingroup$


Let $f:Mto N$ be a smooth bijection between manifolds with same dimension. Do we necessarily have



$$df_p(T_pM)=T_{f(p)}N.$$



I think it is probably not true. But I can't give a counterexample...










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$endgroup$

















    1












    $begingroup$


    Let $f:Mto N$ be a smooth bijection between manifolds with same dimension. Do we necessarily have



    $$df_p(T_pM)=T_{f(p)}N.$$



    I think it is probably not true. But I can't give a counterexample...










    share|cite|improve this question









    $endgroup$















      1












      1








      1





      $begingroup$


      Let $f:Mto N$ be a smooth bijection between manifolds with same dimension. Do we necessarily have



      $$df_p(T_pM)=T_{f(p)}N.$$



      I think it is probably not true. But I can't give a counterexample...










      share|cite|improve this question









      $endgroup$




      Let $f:Mto N$ be a smooth bijection between manifolds with same dimension. Do we necessarily have



      $$df_p(T_pM)=T_{f(p)}N.$$



      I think it is probably not true. But I can't give a counterexample...







      differential-geometry smooth-manifolds






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      asked Dec 11 '18 at 16:34









      No OneNo One

      2,0371519




      2,0371519






















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          $begingroup$

          The map $f:mathbb{R}tomathbb{R}$ given by $f:xmapsto x^3$ is a smooth bijection but $df_0(T_0mathbb{R}) = 0neq T_{f(0)}mathbb{R}$.






          share|cite|improve this answer









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            1












            $begingroup$

            How about $f: mathbb{R} to mathbb{R}$ by $f(x)=x^3$? Certainly smooth, certainly bijective. However, $df_0$ will map the $1$-dimensional tangent space to a point. The root issue is that a smooth bijection can still have critical points.






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              2 Answers
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              $begingroup$

              The map $f:mathbb{R}tomathbb{R}$ given by $f:xmapsto x^3$ is a smooth bijection but $df_0(T_0mathbb{R}) = 0neq T_{f(0)}mathbb{R}$.






              share|cite|improve this answer









              $endgroup$


















                2












                $begingroup$

                The map $f:mathbb{R}tomathbb{R}$ given by $f:xmapsto x^3$ is a smooth bijection but $df_0(T_0mathbb{R}) = 0neq T_{f(0)}mathbb{R}$.






                share|cite|improve this answer









                $endgroup$
















                  2












                  2








                  2





                  $begingroup$

                  The map $f:mathbb{R}tomathbb{R}$ given by $f:xmapsto x^3$ is a smooth bijection but $df_0(T_0mathbb{R}) = 0neq T_{f(0)}mathbb{R}$.






                  share|cite|improve this answer









                  $endgroup$



                  The map $f:mathbb{R}tomathbb{R}$ given by $f:xmapsto x^3$ is a smooth bijection but $df_0(T_0mathbb{R}) = 0neq T_{f(0)}mathbb{R}$.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Dec 11 '18 at 16:41









                  NealNeal

                  23.8k23886




                  23.8k23886























                      1












                      $begingroup$

                      How about $f: mathbb{R} to mathbb{R}$ by $f(x)=x^3$? Certainly smooth, certainly bijective. However, $df_0$ will map the $1$-dimensional tangent space to a point. The root issue is that a smooth bijection can still have critical points.






                      share|cite|improve this answer









                      $endgroup$


















                        1












                        $begingroup$

                        How about $f: mathbb{R} to mathbb{R}$ by $f(x)=x^3$? Certainly smooth, certainly bijective. However, $df_0$ will map the $1$-dimensional tangent space to a point. The root issue is that a smooth bijection can still have critical points.






                        share|cite|improve this answer









                        $endgroup$
















                          1












                          1








                          1





                          $begingroup$

                          How about $f: mathbb{R} to mathbb{R}$ by $f(x)=x^3$? Certainly smooth, certainly bijective. However, $df_0$ will map the $1$-dimensional tangent space to a point. The root issue is that a smooth bijection can still have critical points.






                          share|cite|improve this answer









                          $endgroup$



                          How about $f: mathbb{R} to mathbb{R}$ by $f(x)=x^3$? Certainly smooth, certainly bijective. However, $df_0$ will map the $1$-dimensional tangent space to a point. The root issue is that a smooth bijection can still have critical points.







                          share|cite|improve this answer












                          share|cite|improve this answer



                          share|cite|improve this answer










                          answered Dec 11 '18 at 16:41









                          RandallRandall

                          9,97611230




                          9,97611230






























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