$B$-Stable Ideals in the Nilradical of a Borel Subalgebra
Printed: Sep 2005
We count the number of strictly positive $B$-stable ideals in the
nilradical of a Borel subalgebra and prove that
the minimal roots of any $B$-stable ideal are conjugate
by an element of the Weyl group to a subset of the simple roots.
We also count the number of ideals whose minimal roots are conjugate
to a fixed subset of simple roots.
20F55 - Reflection and Coxeter groups [See also 22E40, 51F15]
17B20 - Simple, semisimple, reductive (super)algebras
05E99 - None of the above, but in this section