Existence of Thom Class












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In page 133, Theorem 8.5.5.




(The Thom isomoprhism theorem) Let $pi:V rightarrow X$ be a complex vector bundle of rank $n$, over al locally comapct space $X$. Let
$$ 0 rightarrow pi^* wedge ^0 V rightarrow pi^* wedge ^1 V rightarrow cdots rightarrow pi^* wedge ^n V rightarrow0 $$
we the chain complex, the map $pi^* wedge ^pV rightarrow pi^* wedge ^{p+1} V$ is given over $v in V$ by taking the exterior product with $v$. The Thom class $t_V in K_c(V)$ is the complex conjugate of the wrap of this complex. Then the map
$$ th^K:K_c(X) rightarrow K_c(V), : , x mapsto pi^*x # t_V $$
is an isomoprhism.




The remark says:




We do not need to know the Thom isomoprhism theorem, but only the existence of the Thom Class.




I'm confused with this statement. Is there something needed to prove for the existence?



I think what we have to prove is that $t_V$ is indeed an element of $K_c(V)$? How is this justified?










share|cite|improve this question











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    0












    $begingroup$


    In page 133, Theorem 8.5.5.




    (The Thom isomoprhism theorem) Let $pi:V rightarrow X$ be a complex vector bundle of rank $n$, over al locally comapct space $X$. Let
    $$ 0 rightarrow pi^* wedge ^0 V rightarrow pi^* wedge ^1 V rightarrow cdots rightarrow pi^* wedge ^n V rightarrow0 $$
    we the chain complex, the map $pi^* wedge ^pV rightarrow pi^* wedge ^{p+1} V$ is given over $v in V$ by taking the exterior product with $v$. The Thom class $t_V in K_c(V)$ is the complex conjugate of the wrap of this complex. Then the map
    $$ th^K:K_c(X) rightarrow K_c(V), : , x mapsto pi^*x # t_V $$
    is an isomoprhism.




    The remark says:




    We do not need to know the Thom isomoprhism theorem, but only the existence of the Thom Class.




    I'm confused with this statement. Is there something needed to prove for the existence?



    I think what we have to prove is that $t_V$ is indeed an element of $K_c(V)$? How is this justified?










    share|cite|improve this question











    $endgroup$















      0












      0








      0


      1



      $begingroup$


      In page 133, Theorem 8.5.5.




      (The Thom isomoprhism theorem) Let $pi:V rightarrow X$ be a complex vector bundle of rank $n$, over al locally comapct space $X$. Let
      $$ 0 rightarrow pi^* wedge ^0 V rightarrow pi^* wedge ^1 V rightarrow cdots rightarrow pi^* wedge ^n V rightarrow0 $$
      we the chain complex, the map $pi^* wedge ^pV rightarrow pi^* wedge ^{p+1} V$ is given over $v in V$ by taking the exterior product with $v$. The Thom class $t_V in K_c(V)$ is the complex conjugate of the wrap of this complex. Then the map
      $$ th^K:K_c(X) rightarrow K_c(V), : , x mapsto pi^*x # t_V $$
      is an isomoprhism.




      The remark says:




      We do not need to know the Thom isomoprhism theorem, but only the existence of the Thom Class.




      I'm confused with this statement. Is there something needed to prove for the existence?



      I think what we have to prove is that $t_V$ is indeed an element of $K_c(V)$? How is this justified?










      share|cite|improve this question











      $endgroup$




      In page 133, Theorem 8.5.5.




      (The Thom isomoprhism theorem) Let $pi:V rightarrow X$ be a complex vector bundle of rank $n$, over al locally comapct space $X$. Let
      $$ 0 rightarrow pi^* wedge ^0 V rightarrow pi^* wedge ^1 V rightarrow cdots rightarrow pi^* wedge ^n V rightarrow0 $$
      we the chain complex, the map $pi^* wedge ^pV rightarrow pi^* wedge ^{p+1} V$ is given over $v in V$ by taking the exterior product with $v$. The Thom class $t_V in K_c(V)$ is the complex conjugate of the wrap of this complex. Then the map
      $$ th^K:K_c(X) rightarrow K_c(V), : , x mapsto pi^*x # t_V $$
      is an isomoprhism.




      The remark says:




      We do not need to know the Thom isomoprhism theorem, but only the existence of the Thom Class.




      I'm confused with this statement. Is there something needed to prove for the existence?



      I think what we have to prove is that $t_V$ is indeed an element of $K_c(V)$? How is this justified?







      algebraic-topology vector-bundles k-theory topological-k-theory






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Dec 19 '18 at 15:35







      CL.

















      asked Dec 10 '18 at 1:56









      CL.CL.

      2,2482825




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