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Questions about the properties of vector spaces and linear transformations, including linear systems in general.

6 votes
2 answers
801 views

Cyclic vectors in irreducible representations of simple Lie algebras

Is there a notion of "cyclic element" in a simple Lie algebra? In particular, is it independent of the irreducible representation chosen? Explanation. An endomorphism A is called cyclic if there …
AThomas's user avatar
  • 617
4 votes
2 answers
352 views

Double centralizer in special linear algebra

It is well known that for a matrix $A$ in $\mathfrak{sl}_n(\mathbb{C})$, we have the following equivalence: $$\dim Z(A) \text{ is minimal} \leftrightarrow A \text{ is cyclic}$$ where $Z(A)$ is the cen …
AThomas's user avatar
  • 617
0 votes
Accepted

Double centralizer in special linear algebra

I just found a counter-example for $\mathfrak{sl}_3$. Take $A= \begin{bmatrix} 0 & 1 & 0 \\ 0 & 0 & 0 \\ 0 & 0 & 0 \end{bmatrix}$ and $B = \begin{bmatrix} 0 & 0 & 1 \\ 0 & 0 & 0 \\ 0 & 0 & 0 \end{bm …
AThomas's user avatar
  • 617