- Commit
- e12c00b7b87a0354f307db3fc3edc280cfbced98
- Parent
- f1ad85a0a6b74edba847dc577eddf086acedaf1e
- Author
- Pablo <pablo-escobar@riseup.net>
- Date
Cleaned TODO items
Some of this items have already been dealt with.
Source code for my notes on representations of semisimple Lie algebras and Olivier Mathieu's classification of simple weight modules
Cleaned TODO items
Some of this items have already been dealt with.
3 files changed, 0 insertions, 15 deletions
Status | File Name | N° Changes | Insertions | Deletions |
Modified | TODO.md | 3 | 0 | 3 |
Modified | sections/mathieu.tex | 7 | 0 | 7 |
Modified | sections/semisimple-algebras.tex | 5 | 0 | 5 |
diff --git a/TODO.md b/TODO.md @@ -1,8 +1,5 @@ # TODO -* Write something on the motivation for the representation theory of Lie - algebras - * The geometric realization of the universal enveloping algebra and D-modules * Comment on the geometric realization of the irreducible representations of sl2 * Add some comments on how the concept of coherent families is useful to other
diff --git a/sections/mathieu.tex b/sections/mathieu.tex @@ -17,7 +17,6 @@ classification of completely reducible representations. Our strategy is, once again, to classify the irreducible representations. % TODO: Add references to the motivation -% TODO: Point out that U(g) is always a domain in the introduction Secondly, and this is more important, we now consider \emph{infinite-dimensional} representations too. The motivation behind looking at infinite-dimensional modules was already explained in the introduction, but @@ -204,9 +203,6 @@ the following definition. if \(\mathfrak{b} \subset \mathfrak{p}\). \end{definition} -% TODO: Define nilpotent algebras beforehand TODO: Define the nilradical in the -% introduction and state that the quotient of an alebra by its nilradical is -% reductive TODO: State the universal property of quotients in the introduction Parabolic subalgebras thus give us a process for constructing weight \(\mathfrak{g}\)-modules from representations of smaller (parabolic) subalgebras. Our hope is that by iterating this process again and again we can @@ -363,8 +359,6 @@ a cuspidal representations we have encoutered so far: the \(\mathfrak{sl}_2(K)\)-module \(K[x, x^{-1}]\) of Laurent polynomials -- i.e. example~\ref{ex:laurent-polynomial-mod}. -% TODO: Add a reference to Coutinho or something on the definition of the ring -% of differential operators of a given algebra Our first observation is that \(\mathfrak{sl}_2(K)\) acts in \(K[x, x^{-1}]\) via differential operators. In other words, the action map \(\mathcal{U}(\mathfrak{sl}_2(K)) \to \operatorname{End}(K[x, x^{-1}])\) @@ -547,7 +541,6 @@ that a ``semisimple'' is a synonim for ``completely reducible'' in the context of modules.} of a coherent family}, which takes a coherent extension of \(V\) to a completely reducible coherent extension of \(V\). -% TODO: Note somewhere that M[mu] is a submodule % Mathieu's proof of this is somewhat profane, I don't think it's worth % including it in here \begin{lemma}\label{thm:component-coh-family-has-finite-length}
diff --git a/sections/semisimple-algebras.tex b/sections/semisimple-algebras.tex @@ -577,7 +577,6 @@ We are now finally ready to prove\dots \end{tikzcd} \end{center} - % TODO: Define the action of g in Hom(V, W) beforehand Now notice \(\operatorname{Hom}(U, -)^{\mathfrak{g}} = \operatorname{Hom}_{\mathfrak{g}}(U, -)\). Indeed, given a \(\mathfrak{g}\)-module \(S\) and a \(K\)-linear map \(T : U \to S\) @@ -668,7 +667,6 @@ The primary goal of this section is proving\dots \(V\) of \(\mathfrak{sl}_2(K)\) with \(\dim V = n\). \end{theorem} -% TODO: Point out the standard basis beforehand The general approach we'll take is supposing \(V\) is an irreducible representation of \(\mathfrak{sl}_2(K)\) and then derive some information about its structure. We begin our analysis by recalling that the elements @@ -2193,7 +2191,6 @@ Instead, we need a new strategy for the general setting. To that end, we introduce a special class of \(\mathfrak{g}\)-modules, known as \emph{Verma modules}. -% TODO: Define the induced representation beforehand \begin{definition}\label{def:verma} The \(\mathfrak{g}\)-module \(M(\lambda) = \operatorname{Ind}_{\mathfrak{b}}^{\mathfrak{g}} K v^+\), where the action of @@ -2212,7 +2209,6 @@ construction \(M(\lambda) = \mathcal{U}(\mathfrak{g}) \cdot v^+\) -- where \(v^+ = 1 \otimes v^+ \in M(\lambda)\) is as in definition~\ref{def:verma}. Moreover, we find\dots -% TODO: State the PBW theorem in the introduction \begin{proposition}\label{thm:verma-is-weight-mod} The weight spaces decomposition \[ @@ -2327,7 +2323,6 @@ is neither irreducible nor finite-dimensional. Nevertheless, we can use \(M(\lambda)\) to construct an irreducible representation of \(\mathfrak{g}\) whose highest weight is \(\lambda\). -% TODO: Adjust the notation for the maximal submodule \begin{proposition}\label{thm:max-verma-submod-is-weight} Every subrepresentation \(V \subset M(\lambda)\) is the direct sum of its weight spaces. In particular, \(M(\lambda)\) has a unique maximal