- Commit
- d99a7e177e58a7b02190d93c8c933c23edc3d597
- Parent
- 91b949daea64e734bca7ed4bc4e4b32b4fcff99f
- Author
- Pablo <pablo-escobar@riseup.net>
- Date
Fixed a minor error in the definition of a coherent extension
Also fixed some typos and added comments
Source code for my notes on representations of semisimple Lie algebras and Olivier Mathieu's classification of simple weight modules
Fixed a minor error in the definition of a coherent extension
Also fixed some typos and added comments
1 file changed, 9 insertions, 10 deletions
Status | File Name | N° Changes | Insertions | Deletions |
Modified | sections/mathieu.tex | 19 | 9 | 10 |
diff --git a/sections/mathieu.tex b/sections/mathieu.tex @@ -158,7 +158,7 @@ % TODO: Add an example: there's an example of a coherent sl2-family in % Mathieu's paper -% TODOO: Add a discussion on how this may sound unintuitive, but the motivation +% TODO: Add a discussion on how this may sound unintuitive, but the motivation % comes from the relationship between highest weight modules and coherent % families @@ -170,9 +170,9 @@ \end{definition} \begin{definition} - Given a representation \(V\) of \(\mathfrak{g}\), a coherent extension - \(\mathcal{M}\) of \(V\) is a coherent family \(\mathcal{M}\) that contains - \(V\) as a subquotient. + Given an admissible representation \(V\) of \(\mathfrak{g}\) of degree \(d\), + a coherent extension \(\mathcal{M}\) of \(V\) is a coherent family + \(\mathcal{M}\) of degree \(d\) that contains \(V\) as a subquotient. \end{definition} % Mathieu's proof of this is somewhat profane, I don't think it's worth @@ -283,7 +283,6 @@ s^{-1} = t_2^{-1} u_2\). \end{definition} -% TODOOO: Does R need to be Noetherian? \begin{theorem}[Ore-Asano] Let \(S \subset R\) be a multiplicative subset satisfying Ore's localization condition. Then there exists a (unique) ring \(S^{-1} R\), with a canonical @@ -440,11 +439,13 @@ \Sigma^{-1} V\) is the \(\Sigma^{-1} \mathcal{U}(\mathfrak{g})\)-module \(\Sigma^{-1} V\) twisted by the automorphism \(\theta_\lambda\) then \(\Sigma^{-1} V_\mu = (\theta_\lambda \Sigma^{-1} V)_{\mu + \lambda}\). + In particular, \(\operatorname{supp} \theta_\lambda \Sigma^{-1} V = + \lambda + Q + \operatorname{supp} V\). \end{enumerate} \end{proposition} \begin{proposition}[Mathieu] - There exists a coherent extension \(\mathcal{M}\) of \(V\) with degree \(d\). + There exists a coherent extension \(\mathcal{M}\) of \(V\). \end{proposition} \begin{proof} @@ -480,12 +481,10 @@ \end{theorem} % TODOOO: Prove the uniqueness -% TODOO: Does every coherent extension of V have the same degree as V? \begin{proof} The existence part should be clear from the previous discussion: let - \(\mathcal{M}\) be a coherent extension of \(V\) with \(\deg \mathcal{M} = - d\) and take \(\operatorname{Ext}(V) = \mathcal{M}^{\operatorname{ss}}\) of - \(V\). + \(\mathcal{M}\) be a coherent extension of \(V\) and take + \(\operatorname{Ext}(V) = \mathcal{M}^{\operatorname{ss}}\) of \(V\). We claim \(V\) is contained in \(\operatorname{Ext}(V)\). Indeed, if we fix some composition series \(0 =