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Fine gradings of complex simple Lie algebras and Finite Root Systems
A -grading on a complex semisimple Lie algebra , where is a finite
abelian group, is called quasi-good if each homogeneous component is
1-dimensional and 0 is not in the support of the grading.
Analogous to classical root systems, we define a finite root system to be
some subset of a finite symplectic abelian group satisfying certain axioms.
There always corresponds to a semisimple Lie algebra together with a
quasi-good grading on it. Thus one can construct nice basis of by means
of finite root systems.
We classify finite maximal abelian subgroups in \Aut(L) for complex
simple Lie algebras such that the grading induced by the action of on
is quasi-good, and show that the set of roots of in is always a
finite root system. There are five series of such finite maximal abelian
subgroups, which occur only if is a classical simple Lie algebra
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