"Bruhat decomposition"의 두 판 사이의 차이

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imported>Pythagoras0
imported>Pythagoras0
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==introduction==
 
==introduction==
* double Bruhat cells
 
 
* Bruhat order
 
* Bruhat order
 
* Weyl group action 
 
* Weyl group action 
* The decomposition of G into strata G^{u,v} is 'good with respect to total positivity.
 
  
  
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* Double cosets <math>BwB</math> and <math>B_{-}wB_{-}</math> are called Bruhat cells.
 
* Double cosets <math>BwB</math> and <math>B_{-}wB_{-}</math> are called Bruhat cells.
  
 
 
 
==double Bruhat cell (DBC)==
 
 
* <math>G^{u,v} =BuB\cap B_{-}vB_{-}</math>
 
* <math>G=\cup_{u,v\in W\times W} G^{u,v}</math> (disjoint union)
 
 
 
 
 
 
 
 
==realization of finite type cluster algebra==
 
 
* Yang, Shih-Wei, 와/과Andrei Zelevinsky. 2008. “Cluster algebras of finite type via Coxeter elements and principal minors”. <em>0804.3303</em> (4월 21). http://arxiv.org/abs/0804.3303.
 
* <math>\mathbb{C}[L^{c,c^{-1}}]</math> is a cluster algebra of finite type. It has the same type as Cartan matrix.
 
  
 
 
 
===type A_{n}===
 
* (i) inite seed is given by $x=(x_{[1,1]},\cdots,x_{[1,n]})$, $y=(y_1,\cdots,y_n)$, $B=B(C)$
 
* (ii) The set of cluster variables is \{x_{[i,j]}|1\leq i\leq j\leq n \}
 
* (iii) The exchange relations
 
$$x_{[i,k]}x_{[j,l]} = y_{j-1}y_{j}\cdots y_{k} x_{[i,j-2]}jx_{[i,j-2]}+x_{[i,l]}x_{[j,l]}$$ for $1\leq i\leq j-1\leq k\leq l-1\leq n$
 
* remark : $x_{[i,j]}$ corresponds to the diagonal between i and j in the triangulation of regular $(n+3)$-gon
 
 
 
 
 
==example==
 
* [[double Bruhat cell example]]
 
  
  
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==related items==
 
* [[Total positivity]]
 
  
 
 
  
 
==encyclopedia==
 
==encyclopedia==
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==expositions==
 
==expositions==
 
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* Lusztig, G. 2010. “Bruhat Decomposition and Applications.” arXiv:1006.5004 [math] (June 25). http://arxiv.org/abs/1006.5004.
* http://www-math.mit.edu/~gyuri/papers/bru1.pdf
 
* http://pages.uoregon.edu/dmoseley/talks/
 
** [http://pages.uoregon.edu/dmoseley/talks/Lecture14.pdf Double Bruhat Cells]
 
** [http://pages.uoregon.edu/dmoseley/talks/Lecture15.pdf Cluster Structures on Double Bruhat Cells]
 
 
* http://math.ucr.edu/home/baez/week186.html
 
* http://math.ucr.edu/home/baez/week186.html
* http://www.math.harvard.edu/~ryanr/bruhat_row-reduction.pdf
+
* [http://www.ryancreich.info/bruhat_row-reduction.pdf Bruhat decomposition via row reduction]
  
 
 
 
 
 
==articles==
 
*  Yang, Shih-Wei, 와/과Andrei Zelevinsky. 2008. “Cluster algebras of finite type via Coxeter elements and principal minors”. <em>0804.3303</em> (4월 21). http://arxiv.org/abs/0804.3303.<br>
 
 
  
  

2013년 12월 7일 (토) 07:08 판

introduction

  • Bruhat order
  • Weyl group action 


Bruhat cell

  • $G=GL_{n}$
  • $B$ : upper triangular matrices in $G$
  • $B_{-}$ : lower triangular matrices in $G$
  • $W=S_{n}$ we can think of it as a subgroup of $G$
  • Double cosets \(BwB\) and \(B_{-}wB_{-}\) are called Bruhat cells.



memo


computational resource

 


encyclopedia


expositions

 


question and answers(Math Overflow)