Questions tagged [verma-modules]
Verma modules, are objects in the representation theory of Lie algebras that can be used in the classification of irreducible representations of a complex semisimple Lie algebra
32 questions
1 vote
0 answers
74 views
Character of a kac-moody module as the sum of characters of Verma modules
I'm trying to prove the next result from Kac's book, Infinite dimensional Lie algebras. Let $V$ be a $\mathfrak{g}(A)$-module with highest weight $\Lambda$. Then $$ \text{ch}(V)=\sum_{\lambda\in B(\...
1 vote
0 answers
73 views
A particular quotient in the study of tensor products of $\mathfrak{sl}_2$-modules
I’m studying Verma modules of $\mathfrak{sl}_{2} = \mathfrak{sl}_{2} (\mathbb{C})$. Let’s introduce standard notation. Elements $h,e,f\in \mathfrak{sl}_{2} $ form the basis of $\mathfrak{sl}_{2}$, ...
2 votes
0 answers
113 views
Verma modules as representations of the Borel
Let $T \subset B \subset G$ be a reductive group, a Borel subgroup and a maximal torus over a field of characteristic $0$, with respective Lie algebras $\mathfrak{b} \subset \mathfrak{g}$. For a ...
2 votes
0 answers
52 views
Filtration of Verma modules tensored with a simple module
Let $L_m$ be the $m+1$ dimensional simple module over $\mathfrak{sl}_2(\Bbb{C})$, and $M_\lambda,\; \lambda\in \Bbb C$, the Verma module with highest weight $\lambda$ over $\frak{sl}_2(\Bbb C)$. Show ...
3 votes
1 answer
200 views
Question about definition of Verma modules
I am studying Verma modules (reading Dixmier´s Enveloping Algebras) and have a question regarding the definition as a quotieng of the enveloping algebra. Let $g$ be a Lie algebra and $h$ its Cartan ...
0 votes
0 answers
84 views
Irreducible finite-dimensional real $\mathfrak{sl}_2(\mathbb R)$-representations
It is easy to show that every irreducible finite-dimensional real $\mathfrak{sl}_2(\mathbb C)$-representation is a weight module. The operator commonly denoted as $h$ in $\mathfrak{sl}_2$ has an ...
3 votes
1 answer
542 views
Intuition behind verma modules
What is the intuition behind verma modules? Their construction is quite technical to me and I know they help classify irreducible representations and are very useful, but I cannot see how. In class, ...
0 votes
0 answers
123 views
Counting the multiplicity of weight of a Verma module without using the Kostant partition function or the Weyl character formula.
For a semisimple Lie algebra $\mathfrak{g}$ and a Cartan subalgebra $\mathfrak{h}$, if $\mu \in \mathfrak{h}$ and $W_{\mu}$ is the associated Verma module, I want to see that the multiplicity of $\...
1 vote
0 answers
91 views
Constructing a surjective intertwining map onto Verma module
I want to prove the following result: Theorem: Let $\mathfrak{g}$ be a semi-simple Lie algebra, $\mathfrak{h}$ be a Cartan subalgebra, $\mu \in \mathfrak{h}$, and $W_{\mu} = \mathfrak{U}_{\mathfrak{g}...
1 vote
1 answer
178 views
Simple quotient of Verma Module $ M_\mathfrak{b}(\lambda) $
I'm starting to look into Lie Superalgebras and understand a bit more about simple f.d. modules. Right now I'm studying fairly simple examples to try and get a feel for it. I'm trying to find the ...
5 votes
1 answer
241 views
Character formula of Verma module over a Kac-Moody algebra
The character formula of a Verma module over a Kac-Moody algebra is given by $$\textrm{ch}\ M(\Lambda)=\frac{e(\Lambda)}{\prod_{\alpha\in\Phi+}(1-e(-\alpha))^{\textrm{mult}(\alpha)}}$$ Here $\Phi_+$ ...
2 votes
0 answers
121 views
Basic representation of a simple Lie algebra and its highest weight
I have come across the terms "basic representation" of a semisimple Lie algebra, but I am finding it hard to find a clear definition of this representation. Can someone provide me a ...
3 votes
0 answers
63 views
Equivalence of verma modules
Let $R^+$ be the set of positive roots and $L_\alpha$ the root space to $\alpha \in R^+$. $\mathfrak{h}$ is a Cartan subalgebra of L. Let $I_\lambda$ be the left ideal of $U(L)$ which is generated by ...
1 vote
0 answers
40 views
Embedding of Verma modules in Kac-Moody Lie algebras
Let $\mathfrak{g}(A)$ be a symmetrizable Kac-Moody Lie algebra over $\mathbb{C}$ and ($\mathfrak{h}$, $\Pi, \Pi^\vee)$ be a realization of the GCM $A$. Assume that $$\mathfrak{g}(A)=\mathfrak{h} \...
4 votes
2 answers
972 views
How to show a Verma module is irreducible
Let $g$ be a semi simple Lie algebra, $\rho$ be the half sum of all positive roots. I want to show that The Verma module $M(-\rho)$ is irreducible I have no idea how to approache this. Any hint or ...