MHB Can Different Bases Change the Classification of Lie Algebras?

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Changing bases in Lie algebras, such as from su2 to sl2, can lead to confusion due to their differing structure constants, raising questions about accuracy in terminology. The instructor's use of "su2" when referring to "sl2" may reflect a common practice in physics where precision is sometimes sacrificed for simplicity. Additionally, transitioning from a Cartan-Weyl basis to a Chevalley basis in sl3 alters the properties of the root system, complicating the classification. Despite these differences, texts often continue to refer to the algebras by their original names, which can mislead readers about their structural characteristics. This discussion highlights the need for clarity in the classification of Lie algebras when changing bases.
topsquark
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This is only a minor question.

I watched an on-line video recently on su2 and how it applies to Physics. Now, one of the first things the instructor did was to change the base to sl2. Fine and all, but she called sl2 "su2" for the whole video. Since the two Lie algebras have different structure factors how can she do this? Or was she just being a Physicist and sloppy about it?

Another example. My text is talking about the Cartan-Weyl basis of sl3, then changes the basis to a Chevalley basis. The problem here is not merely that the structure factors are different but now the simply laced root system for the Cartan basis is no longer simply laced in the Chevalley basis. And yet the text still refers to it as sl3.

What gives?

-Dan
 
I am studying the mathematical formalism behind non-commutative geometry approach to quantum gravity. I was reading about Hopf algebras and their Drinfeld twist with a specific example of the Moyal-Weyl twist defined as F=exp(-iλ/2θ^(μν)∂_μ⊗∂_ν) where λ is a constant parametar and θ antisymmetric constant tensor. {∂_μ} is the basis of the tangent vector space over the underlying spacetime Now, from my understanding the enveloping algebra which appears in the definition of the Hopf algebra...

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