English
The Lie algebra LieAlgebra(b) is spanned by the elements h,e,f corresponding to the crystallographic root data, forming the ambient Lie algebra for Geck's construction.
Русский
Ли-алгебра LieAlgebra(b) порождена элементами h,e,f, соответствующими кристаллографическим данным корней, образуя внешнюю Ли-алгебру для конструирования Geck.
LaTeX
$$$\operatorname{lieAlgebra}(b) = \operatorname{LieSpan}(R,\{h_i,e_i,f_i : i\in b.support\})$$$
Lean4
/-- The element `h i`, as a term of the Cartan subalgebra `cartanSubalgebra' b`. -/
def h' [Fintype ι] [DecidableEq ι] (i : b.support) : cartanSubalgebra' b :=
⟨⟨h i, h_mem_lieAlgebra i⟩, h_mem_cartanSubalgebra' i (h_mem_lieAlgebra i)⟩