Notation
It is customary to express a Lie algebra in lower-case fraktur, like . If a Lie algebra is associated with a Lie group, then the spelling of the Lie algebra is the same as that Lie group. For example, the Lie algebra of SU(n) is written as . (Lie groups corresponding to a Lie algebra is not unique in general. See the section Relation to Lie groups below.)
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