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Lie algebras are algebraic structures which were introduced to study the concept of infinitesimal transformations. The term "Lie algebra" (after Sophus Lie) was introduced by Hermann Weyl in the 1930s. In older texts, the name "infinitesimal group" is used. Related mathematical concepts include Lie groups and differentiable manifolds.

2 votes

Symmetry of Casimirs of Lie algebras

Please expand your definition of "Casimir". Is a $g$-invariant element in $g^{\otimes n}$? If $g$ is a simple algebra and $\kappa$ its Killing form, then the map $$g\times g\times g\to k$$ $$(x,y,z) …
Marco Farinati's user avatar
-1 votes

First adjoint cohomology space of simple Lie algebras

I don't known if I interprete correctly your question. First, if $g$ is simple, then always $H^1(g,g)=0$. ALSO, $H^1(L,L)=0$ do not implies that $L$ is a central extensión of a simple algebra.For exam …
Marco Farinati's user avatar
1 vote

infinite fold tensor product of universal enveloping algebra

Assuming $\infty$= the cardinality of some set $I$, then consider the Lie algebra $\mathfrak a^{(I)}$= the direct sum of $I$-copies of $\mathfrak a$, with bracket coordinatewise. Then take its univers …
Marco Farinati's user avatar
0 votes

What is the cubic Casimir element of $\mathfrak{sl}_3$?

I think $\sum_{i,j,k}X_{ij}X_{jk}X_{ki}$ should work for $\mathfrak{gl}(3)$. Now if you want for $\mathfrak{sl}(3)$, maybe you can change $X_{ii}$ by $X_{ii}-(1/3)\mathrm{Id}$. The formula above is li …
Marco Farinati's user avatar
2 votes

Lie algebra of a compact Lie group and derivations of the Hopf algebra of representative fun...

Some years ago we did something that -I think- answers the algebraic version of your question [FS]. If you have a Hopf algebra $H$, then the counit gives you a map $\varepsilon_* :\mathrm{Hom}(H,H)\t …
Marco Farinati's user avatar
3 votes

Classifications of Lie bialgebras

Sorry for the self publicity, but for the especific example of $gl_n(k)$, you can view it as $gl_n(k)\cong sl_n(k)\times k$ and we did some work for trivial central extensions that allow you to produc …
Marco Farinati's user avatar