Nilpotent cone explained

In mathematics, the nilpotent cone

l{N}

of a finite-dimensional semisimple Lie algebra

ak{g}

is the set of elements that act nilpotently in all representations of

ak{g}.

In other words,

l{N}=\{a\inak{g}:\rho(a)isnilpotentforallrepresentations\rho:ak{g}\to\operatorname{End}(V)\}.

The nilpotent cone is an irreducible subvariety of

ak{g}

(considered as a vector space).

Example

The nilpotent cone of

\operatorname{sl}2

, the Lie algebra of 2×2 matrices with vanishing trace, is the variety of all 2×2 traceless matrices with rank less than or equal to

1.

References