Restriction of Bruhat order to stabilizer of a vector











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Let $W$ be a Weyl group (maybe better a Coxeter group, i.e. a group with action on vector space $V$ generated by reflections with some conditions). Consider $v in V$ be a vector. Let $text{Stab}_v subset W$ be a stabilizer of vector $v$.



Theorem
Group $text{Stab}_v$ is generated by reflections.



This Theorem is stated for example here, Theorem 1 (iii).
(in the case of Weyl group $text{Stab}_v$ is a Weyl group of Lie subgroup).



If we choose simple reflections in $W$ we will get a Bruhat order (I am interested in strong Bruhat order). Hence $text{Stab}_v$ is generated by reflections we can choose a set of simple reflections for $text{Stab}_v$; it gives as an interior Bruhat order on $text{Stab}_v$ (which a priori has nothing to do with the Bruhat order on whole $W$).




Is it true that for any choice of simple reflections in $W$ we can
find a set of simple reflections in $text{Stab}_v$ such that
restriction of Bruhat order from $W$ to $text{Stab}_v$ coincides with the
interior Bruhat order on $text{Stab}_v$?











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    up vote
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    down vote

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    Let $W$ be a Weyl group (maybe better a Coxeter group, i.e. a group with action on vector space $V$ generated by reflections with some conditions). Consider $v in V$ be a vector. Let $text{Stab}_v subset W$ be a stabilizer of vector $v$.



    Theorem
    Group $text{Stab}_v$ is generated by reflections.



    This Theorem is stated for example here, Theorem 1 (iii).
    (in the case of Weyl group $text{Stab}_v$ is a Weyl group of Lie subgroup).



    If we choose simple reflections in $W$ we will get a Bruhat order (I am interested in strong Bruhat order). Hence $text{Stab}_v$ is generated by reflections we can choose a set of simple reflections for $text{Stab}_v$; it gives as an interior Bruhat order on $text{Stab}_v$ (which a priori has nothing to do with the Bruhat order on whole $W$).




    Is it true that for any choice of simple reflections in $W$ we can
    find a set of simple reflections in $text{Stab}_v$ such that
    restriction of Bruhat order from $W$ to $text{Stab}_v$ coincides with the
    interior Bruhat order on $text{Stab}_v$?











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      Let $W$ be a Weyl group (maybe better a Coxeter group, i.e. a group with action on vector space $V$ generated by reflections with some conditions). Consider $v in V$ be a vector. Let $text{Stab}_v subset W$ be a stabilizer of vector $v$.



      Theorem
      Group $text{Stab}_v$ is generated by reflections.



      This Theorem is stated for example here, Theorem 1 (iii).
      (in the case of Weyl group $text{Stab}_v$ is a Weyl group of Lie subgroup).



      If we choose simple reflections in $W$ we will get a Bruhat order (I am interested in strong Bruhat order). Hence $text{Stab}_v$ is generated by reflections we can choose a set of simple reflections for $text{Stab}_v$; it gives as an interior Bruhat order on $text{Stab}_v$ (which a priori has nothing to do with the Bruhat order on whole $W$).




      Is it true that for any choice of simple reflections in $W$ we can
      find a set of simple reflections in $text{Stab}_v$ such that
      restriction of Bruhat order from $W$ to $text{Stab}_v$ coincides with the
      interior Bruhat order on $text{Stab}_v$?











      share|cite|improve this question















      Let $W$ be a Weyl group (maybe better a Coxeter group, i.e. a group with action on vector space $V$ generated by reflections with some conditions). Consider $v in V$ be a vector. Let $text{Stab}_v subset W$ be a stabilizer of vector $v$.



      Theorem
      Group $text{Stab}_v$ is generated by reflections.



      This Theorem is stated for example here, Theorem 1 (iii).
      (in the case of Weyl group $text{Stab}_v$ is a Weyl group of Lie subgroup).



      If we choose simple reflections in $W$ we will get a Bruhat order (I am interested in strong Bruhat order). Hence $text{Stab}_v$ is generated by reflections we can choose a set of simple reflections for $text{Stab}_v$; it gives as an interior Bruhat order on $text{Stab}_v$ (which a priori has nothing to do with the Bruhat order on whole $W$).




      Is it true that for any choice of simple reflections in $W$ we can
      find a set of simple reflections in $text{Stab}_v$ such that
      restriction of Bruhat order from $W$ to $text{Stab}_v$ coincides with the
      interior Bruhat order on $text{Stab}_v$?








      combinatorics reflection root-systems coxeter-groups weyl-group






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      edited Nov 13 at 5:20

























      asked Nov 12 at 16:33









      quinque

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