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[parent] Jacobi identity interpretations (Definition)

The Jacobi identity in a Lie algebra $\mathfrak{g}$ has various interpretations that are more transparent, whence easier to remember, than the usual form $$ [x,[y,z]]+[y,[z,x]]+[z,[x,y]]=0. $$ One is the fact that the adjoint representation 1$\ad:\mathfrak{g} \rightarrow \mathfrak{gl}(\mathfrak{g})$ really is a representation. Yet another way to formulate the identity is $$ \ad(x)[y,z]=[\ad(x)y,z]+[y,\ad(x)z], $$ i.e., $\ad(x)$ is a derivation on $\mathfrak{g}$ for all $x \in \mathfrak{g}$



Footnotes

...http://planetmath.org/encyclopedia/AdjointAction.html 1
Here, ``$\mathfrak{gl}(\mathfrak{g})$ ' means the space o endomorphisms of $\mathfrak{g}$ viewed as a vector space, with Lie bracket on $\mathfrak{gl}(\mathfrak{g})$ commutator.



"Jacobi identity interpretations" is owned by rspuzio. [ full author list (3) | owner history (3) ]
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Cross-references: derivation, identity, representation, commutator, Lie bracket, vector space, endomorphisms, adjoint representation, interpretations, Lie algebra, Jacobi identity

This is version 5 of Jacobi identity interpretations, born on 2002-09-20, modified 2007-04-01.
Object id is 3468, canonical name is JacobiIdentityInterpretations.
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Classification:
AMS MSC17B99 (Nonassociative rings and algebras :: Lie algebras and Lie superalgebras :: Miscellaneous)

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