- Commit
- dd64c565958db73ddade66f91d07efd19946ba6b
- Parent
- 9254cd7294b0453294327a77019176db372a91bd
- Author
- Pablo <pablo-escobar@riseup.net>
- Date
Revised the forth chapter
Source code for my notes on representations of semisimple Lie algebras and Olivier Mathieu's classification of simple weight modules
Revised the forth chapter
1 file changed, 11 insertions, 11 deletions
Status | File Name | N° Changes | Insertions | Deletions |
Modified | sections/semisimple-algebras.tex | 22 | 11 | 11 |
diff --git a/sections/semisimple-algebras.tex b/sections/semisimple-algebras.tex @@ -652,12 +652,12 @@ the argument used for \(\mathfrak{sl}_3(K)\). Namely\dots \end{proposition} The proof of proposition~\ref{thm:irr-subrep-generated-by-vec} is very similar -to that of proposition~\ref{thm:sl3-positive-roots-span-all-irr-rep} in -spirit: we use the commutator relations of \(\mathfrak{g}\) to inductively show -that the subspace spanned by the images of a highest weight vector under -successive applications of negative root vectors is invariant under the action -of \(\mathfrak{g}\) -- please refer to \cite{fulton-harris} for further -details. Of course, what we are really interested in is\dots +in spirit to that of proposition~\ref{thm:sl3-positive-roots-span-all-irr-rep}: +we use the commutator relations of \(\mathfrak{g}\) to inductively show that +the subspace spanned by the images of a highest weight vector under successive +applications of negative root vectors is invariant under the action of +\(\mathfrak{g}\) -- please refer to \cite{fulton-harris} for further details. +Of course, what we are really interested in is\dots \begin{corollary} Let \(V\) and \(W\) be finite-dimensional irreducible @@ -864,10 +864,10 @@ whose highest weight is \(\lambda\). V = \bigoplus_\mu V_\mu = \bigoplus_\mu M(\lambda)_\mu \cap V \] - Since \(M(\lambda) = \mathcal{U}(\mathfrak{g}) \cdot v^+\), \(V\) is a proper - subrepresentation then \(v^+ \notin V\). Hence any proper submodule lies in - the sum of weight spaces other than \(M(\lambda)_\lambda\), so the sum - \(N(\lambda)\) of all such submodules is still proper. This implies + Since \(M(\lambda) = \mathcal{U}(\mathfrak{g}) \cdot v^+\), if \(V\) is a + proper subrepresentation then \(v^+ \notin V\). Hence any proper submodule + lies in the sum of weight spaces other than \(M(\lambda)_\lambda\), so the + sum \(N(\lambda)\) of all such submodules is still proper. This implies \(N(\lambda)\) is the unique maximal subrepresentation of \(M(\lambda)\) and \(L(\lambda) = \sfrac{M(\lambda)}{N(\lambda)}\) is its unique irreducible quotient. @@ -916,7 +916,7 @@ are really interested in is\dots \begin{proof} Let \(V = L(\lambda)\). It suffices to show that its highest weight is \(\lambda\). We have already seen that \(v^+ \in M(\lambda)_\lambda\) is a - highest weight vector. Now since \(v\) lies outside of the maximal + highest weight vector. Now since \(v^+\) lies outside of the maximal subrepresentation of \(M(\lambda)\), the projection \(v^+ + N(\lambda) \in V\) is nonzero.