| Root-reductive Lie algebras are a countable-dimensional analogue of finite-dimensional reductive Lie algebras. Toral subalgebras play an important structural role in representations of these Lie algebras. Unlike in the finite-dimensional case, the maximal toral subalgebras of a root-reductive Lie algebra are not all conjugate. Moreover, they are not necessarily self-centralizing, and we prove instead that their centralizers are nilpotent of depth at most 2. This work is joint with Ivan Penkov and Noah Snyder. |