Elementary question in reductive group












1












$begingroup$


I am very sorry for asking some elementary question.



Let $G$ be a reductive group over a number field $F$ and $N$ a unipotent radical of some parabolic subgroup of $G$.



Then I am wondering whether $G times N$ is a reductive group?



I will appreciate if you give me an answer in this.



Thank you in advance










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  • $begingroup$
    Asking an elementary question is not a problem on this site. Asking any question, with no context is THE problem here. I shouldn't have to tutor you wrt how to ask a good question, given your rep; but please see How to ask a good question.
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    – amWhy
    Dec 17 '18 at 18:15












  • $begingroup$
    The radical of an algebraic group is the largest normal closed, connected,solvable subgroup. A group is reductive if the radical has no unipotent elements. If $R(G)$ is the radical of $G$, what can you say about the radical of $G times N$?
    $endgroup$
    – D_S
    Dec 17 '18 at 18:18






  • 2




    $begingroup$
    Cross-posted: mathoverflow.net/questions/318873
    $endgroup$
    – Watson
    Dec 17 '18 at 18:31






  • 1




    $begingroup$
    Please do not crosspost.
    $endgroup$
    – Dietrich Burde
    Dec 17 '18 at 20:01
















1












$begingroup$


I am very sorry for asking some elementary question.



Let $G$ be a reductive group over a number field $F$ and $N$ a unipotent radical of some parabolic subgroup of $G$.



Then I am wondering whether $G times N$ is a reductive group?



I will appreciate if you give me an answer in this.



Thank you in advance










share|cite|improve this question









$endgroup$












  • $begingroup$
    Asking an elementary question is not a problem on this site. Asking any question, with no context is THE problem here. I shouldn't have to tutor you wrt how to ask a good question, given your rep; but please see How to ask a good question.
    $endgroup$
    – amWhy
    Dec 17 '18 at 18:15












  • $begingroup$
    The radical of an algebraic group is the largest normal closed, connected,solvable subgroup. A group is reductive if the radical has no unipotent elements. If $R(G)$ is the radical of $G$, what can you say about the radical of $G times N$?
    $endgroup$
    – D_S
    Dec 17 '18 at 18:18






  • 2




    $begingroup$
    Cross-posted: mathoverflow.net/questions/318873
    $endgroup$
    – Watson
    Dec 17 '18 at 18:31






  • 1




    $begingroup$
    Please do not crosspost.
    $endgroup$
    – Dietrich Burde
    Dec 17 '18 at 20:01














1












1








1





$begingroup$


I am very sorry for asking some elementary question.



Let $G$ be a reductive group over a number field $F$ and $N$ a unipotent radical of some parabolic subgroup of $G$.



Then I am wondering whether $G times N$ is a reductive group?



I will appreciate if you give me an answer in this.



Thank you in advance










share|cite|improve this question









$endgroup$




I am very sorry for asking some elementary question.



Let $G$ be a reductive group over a number field $F$ and $N$ a unipotent radical of some parabolic subgroup of $G$.



Then I am wondering whether $G times N$ is a reductive group?



I will appreciate if you give me an answer in this.



Thank you in advance







algebraic-groups reductive-groups






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share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Dec 17 '18 at 18:10









user29422user29422

42637




42637












  • $begingroup$
    Asking an elementary question is not a problem on this site. Asking any question, with no context is THE problem here. I shouldn't have to tutor you wrt how to ask a good question, given your rep; but please see How to ask a good question.
    $endgroup$
    – amWhy
    Dec 17 '18 at 18:15












  • $begingroup$
    The radical of an algebraic group is the largest normal closed, connected,solvable subgroup. A group is reductive if the radical has no unipotent elements. If $R(G)$ is the radical of $G$, what can you say about the radical of $G times N$?
    $endgroup$
    – D_S
    Dec 17 '18 at 18:18






  • 2




    $begingroup$
    Cross-posted: mathoverflow.net/questions/318873
    $endgroup$
    – Watson
    Dec 17 '18 at 18:31






  • 1




    $begingroup$
    Please do not crosspost.
    $endgroup$
    – Dietrich Burde
    Dec 17 '18 at 20:01


















  • $begingroup$
    Asking an elementary question is not a problem on this site. Asking any question, with no context is THE problem here. I shouldn't have to tutor you wrt how to ask a good question, given your rep; but please see How to ask a good question.
    $endgroup$
    – amWhy
    Dec 17 '18 at 18:15












  • $begingroup$
    The radical of an algebraic group is the largest normal closed, connected,solvable subgroup. A group is reductive if the radical has no unipotent elements. If $R(G)$ is the radical of $G$, what can you say about the radical of $G times N$?
    $endgroup$
    – D_S
    Dec 17 '18 at 18:18






  • 2




    $begingroup$
    Cross-posted: mathoverflow.net/questions/318873
    $endgroup$
    – Watson
    Dec 17 '18 at 18:31






  • 1




    $begingroup$
    Please do not crosspost.
    $endgroup$
    – Dietrich Burde
    Dec 17 '18 at 20:01
















$begingroup$
Asking an elementary question is not a problem on this site. Asking any question, with no context is THE problem here. I shouldn't have to tutor you wrt how to ask a good question, given your rep; but please see How to ask a good question.
$endgroup$
– amWhy
Dec 17 '18 at 18:15






$begingroup$
Asking an elementary question is not a problem on this site. Asking any question, with no context is THE problem here. I shouldn't have to tutor you wrt how to ask a good question, given your rep; but please see How to ask a good question.
$endgroup$
– amWhy
Dec 17 '18 at 18:15














$begingroup$
The radical of an algebraic group is the largest normal closed, connected,solvable subgroup. A group is reductive if the radical has no unipotent elements. If $R(G)$ is the radical of $G$, what can you say about the radical of $G times N$?
$endgroup$
– D_S
Dec 17 '18 at 18:18




$begingroup$
The radical of an algebraic group is the largest normal closed, connected,solvable subgroup. A group is reductive if the radical has no unipotent elements. If $R(G)$ is the radical of $G$, what can you say about the radical of $G times N$?
$endgroup$
– D_S
Dec 17 '18 at 18:18




2




2




$begingroup$
Cross-posted: mathoverflow.net/questions/318873
$endgroup$
– Watson
Dec 17 '18 at 18:31




$begingroup$
Cross-posted: mathoverflow.net/questions/318873
$endgroup$
– Watson
Dec 17 '18 at 18:31




1




1




$begingroup$
Please do not crosspost.
$endgroup$
– Dietrich Burde
Dec 17 '18 at 20:01




$begingroup$
Please do not crosspost.
$endgroup$
– Dietrich Burde
Dec 17 '18 at 20:01










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