Journal of Lie Theory 32 (2022), No. 1, 087--120
Copyright Heldermann Verlag 2022
The B-Orbits on a Hermitian Symmetric Variety in Characteristic 2
Michele Carmassi
Dip. di Matematica, Università di Pisa, Italy
m.carmassi3@gmail.com
[Abstract-pdf]
Let $G$ be a reductive linear algebraic group over an algebraically closed field $\mathbb{K}$ of characteristic $2$. Fix a parabolic subgroup $P$ such that the corresponding parabolic subgroup over $\mathbb{C}$ has abelian unipotent radical and fix a Levi subgroup $L\subseteq P$. We parametrize the orbits of a Borel $B\subseteq P$ over the Hermitian symmetric variety $G/L$ supposing the root system $\Phi$ is irreducible. For $\Phi$ simply laced we prove a combinatorial characterization of the Bruhat order over these orbits. We also prove a formula to compute the dimension of the orbits from combinatorial characteristics of their representatives.
Keywords: Flag variety, Bruhat order, dimension formula.
MSC: 14M15.
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