Principal series for $operatorname{GL}_2$, question about an exact sequence











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I have a question about Proposition 7.2 of these notes by Gordon Savin.



Here $G = operatorname{GL}_2(F)$ for $F$ a $p$-adic field, $w = begin{pmatrix} 0 & 1 \ 1 & 0 end{pmatrix}$, and $delta$ is the modulus character $delta begin{pmatrix} a_1 \ & a_2 end{pmatrix} = frac{|a_1|}{|a_2|}$.



enter image description here



I follow all the steps in the proof, except for the very last sentence. Maybe I would understand things if I knew what the map



$$0 rightarrow delta^{frac{1}{2}} chi^w rightarrow Ind_B^G(chi)_N$$



was in the first place.










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    I have a question about Proposition 7.2 of these notes by Gordon Savin.



    Here $G = operatorname{GL}_2(F)$ for $F$ a $p$-adic field, $w = begin{pmatrix} 0 & 1 \ 1 & 0 end{pmatrix}$, and $delta$ is the modulus character $delta begin{pmatrix} a_1 \ & a_2 end{pmatrix} = frac{|a_1|}{|a_2|}$.



    enter image description here



    I follow all the steps in the proof, except for the very last sentence. Maybe I would understand things if I knew what the map



    $$0 rightarrow delta^{frac{1}{2}} chi^w rightarrow Ind_B^G(chi)_N$$



    was in the first place.










    share|cite|improve this question
























      up vote
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      down vote

      favorite









      up vote
      0
      down vote

      favorite











      I have a question about Proposition 7.2 of these notes by Gordon Savin.



      Here $G = operatorname{GL}_2(F)$ for $F$ a $p$-adic field, $w = begin{pmatrix} 0 & 1 \ 1 & 0 end{pmatrix}$, and $delta$ is the modulus character $delta begin{pmatrix} a_1 \ & a_2 end{pmatrix} = frac{|a_1|}{|a_2|}$.



      enter image description here



      I follow all the steps in the proof, except for the very last sentence. Maybe I would understand things if I knew what the map



      $$0 rightarrow delta^{frac{1}{2}} chi^w rightarrow Ind_B^G(chi)_N$$



      was in the first place.










      share|cite|improve this question













      I have a question about Proposition 7.2 of these notes by Gordon Savin.



      Here $G = operatorname{GL}_2(F)$ for $F$ a $p$-adic field, $w = begin{pmatrix} 0 & 1 \ 1 & 0 end{pmatrix}$, and $delta$ is the modulus character $delta begin{pmatrix} a_1 \ & a_2 end{pmatrix} = frac{|a_1|}{|a_2|}$.



      enter image description here



      I follow all the steps in the proof, except for the very last sentence. Maybe I would understand things if I knew what the map



      $$0 rightarrow delta^{frac{1}{2}} chi^w rightarrow Ind_B^G(chi)_N$$



      was in the first place.







      representation-theory p-adic-number-theory reductive-groups






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      asked Dec 2 at 4:21









      D_S

      13.1k51551




      13.1k51551






















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          $DeclareMathOperator{Ind}{Ind}$Oh wait, I think I get it. The kernel of $alpha_w: Ind_B^G(chi)_w rightarrow mathbb C$ is exactly $Ind_B^G(chi)_w(N)$, so we get an isomorphism of the Jacquet module $Ind_B^G(chi)_{w,N}$ with $mathbb C$. This is how we get an embedding



          $$mathbb C rightarrow Ind_B^G(chi)_{w,N} rightarrow Ind_B^G(chi)_N$$






          share|cite|improve this answer





















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            $DeclareMathOperator{Ind}{Ind}$Oh wait, I think I get it. The kernel of $alpha_w: Ind_B^G(chi)_w rightarrow mathbb C$ is exactly $Ind_B^G(chi)_w(N)$, so we get an isomorphism of the Jacquet module $Ind_B^G(chi)_{w,N}$ with $mathbb C$. This is how we get an embedding



            $$mathbb C rightarrow Ind_B^G(chi)_{w,N} rightarrow Ind_B^G(chi)_N$$






            share|cite|improve this answer

























              up vote
              0
              down vote













              $DeclareMathOperator{Ind}{Ind}$Oh wait, I think I get it. The kernel of $alpha_w: Ind_B^G(chi)_w rightarrow mathbb C$ is exactly $Ind_B^G(chi)_w(N)$, so we get an isomorphism of the Jacquet module $Ind_B^G(chi)_{w,N}$ with $mathbb C$. This is how we get an embedding



              $$mathbb C rightarrow Ind_B^G(chi)_{w,N} rightarrow Ind_B^G(chi)_N$$






              share|cite|improve this answer























                up vote
                0
                down vote










                up vote
                0
                down vote









                $DeclareMathOperator{Ind}{Ind}$Oh wait, I think I get it. The kernel of $alpha_w: Ind_B^G(chi)_w rightarrow mathbb C$ is exactly $Ind_B^G(chi)_w(N)$, so we get an isomorphism of the Jacquet module $Ind_B^G(chi)_{w,N}$ with $mathbb C$. This is how we get an embedding



                $$mathbb C rightarrow Ind_B^G(chi)_{w,N} rightarrow Ind_B^G(chi)_N$$






                share|cite|improve this answer












                $DeclareMathOperator{Ind}{Ind}$Oh wait, I think I get it. The kernel of $alpha_w: Ind_B^G(chi)_w rightarrow mathbb C$ is exactly $Ind_B^G(chi)_w(N)$, so we get an isomorphism of the Jacquet module $Ind_B^G(chi)_{w,N}$ with $mathbb C$. This is how we get an embedding



                $$mathbb C rightarrow Ind_B^G(chi)_{w,N} rightarrow Ind_B^G(chi)_N$$







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Dec 2 at 4:26









                D_S

                13.1k51551




                13.1k51551






























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