- Commit
- 58802aa295b5db224f0caff9ed5b05fe56c79542
- Parent
- 748544198469c1717ab6a9774af769285e270f70
- Author
- Pablo <pablo-escobar@riseup.net>
- Date
Minor fixes
Source code for my notes on representations of semisimple Lie algebras and Olivier Mathieu's classification of simple weight modules
Minor fixes
1 file changed, 8 insertions, 8 deletions
Status | File Name | N° Changes | Insertions | Deletions |
Modified | sections/mathieu.tex | 16 | 8 | 8 |
diff --git a/sections/mathieu.tex b/sections/mathieu.tex @@ -194,11 +194,11 @@ into the general case. Our goal is now classifying all irreducible weight As a first approximation of a solution to our problem, we consider the induction functors \(\operatorname{Ind}_{\mathfrak{p}}^{\mathfrak{g}} : \mathfrak{p}\text{-}\mathbf{Mod} \to \mathfrak{g}\text{-}\mathbf{Mod}\), where -\(\mathcal{p} \subset \mathfrak{g}\) is some subalgebra. These functors have -already proved themselves a powerful tool for constructing representations. Our -first observation is that if \(\mathfrak{p} \subset \mathfrak{g}\) contains the -Borel \(\mathfrak{b}\) then \(\mathfrak{h} \subset \mathfrak{p}\) is a Cartan -subalgebra of \(\mathfrak{p}\) and +\(\mathfrak{p} \subset \mathfrak{g}\) is some subalgebra. These functors have +already proved themselves a powerful tool for constructing representations in +the previous chapters. Our first observation is that if \(\mathfrak{p} \subset +\mathfrak{g}\) contains the Borel \(\mathfrak{b}\) then \(\mathfrak{h} \subset +\mathfrak{p}\) is a Cartan subalgebra of \(\mathfrak{p}\) and \((\operatorname{Ind}_{\mathfrak{p}}^{\mathfrak{g}} V)_\lambda = \mathcal{U}(\mathfrak{g}) \otimes_{\mathcal{U}(\mathfrak{p})} V_\lambda\) for all \(\lambda \in \mathfrak{h}^*\). In particular, @@ -220,7 +220,7 @@ there's a small catch: a parabolic subalgebra \(\mathfrak{p} \subset \mathfrak{g}\) needs not to be reductive. We can get around this limitation by considering the sum \(\mathfrak{u} \normal \mathfrak{p}\) of all of its nipotent ideals -- i.e. a maximal nilpotent ideal of \(\mathfrak{p}\), known as -\emph{the nilradical of \(\mathfrak{p}\)} and noticing that \(\mathfrak{u}\) +\emph{the nilradical of \(\mathfrak{p}\)} -- and noticing that \(\mathfrak{u}\) acts trivialy in any weight \(\mathfrak{p}\)-module \(V\). By applying the universal property of quotients we can see that \(V\) has the natural structure of a representation of \(\mfrac{\mathfrak{p}}{\mathfrak{u}}\), which is always @@ -283,8 +283,8 @@ words\dots We should point out that the relationship between irreducible weight \(\mathfrak{g}\)-modules and pairs \((\mathfrak{p}, V)\) -- where \(\mathfrak{p}\) is some parabolic subalgebra and \(V\) is an irreducible -cuspidal \(\mathfrak{p}\)-module -- is not one-to-one. In fact, one can -show\dots +cuspidal \(\mathfrak{p}\)-module -- is not one-to-one. Nevertheless, this +relationship is well understood. Namely, Fernando himself established\dots % TODO: Define the conjugation of a p-mod by an element of the Weil group % beforehand