Characteristically nilpotent Lie Algebras: a survey.
A Lie algebra is called 2-step nilpotent if is not abelian and lies in the center of . 2-step nilpotent Lie algebras are useful in the study of some geometric problems, and their classification has been an important problem in Lie theory. In this paper, we give a classification of 2-step nilpotent Lie algebras of dimension 9 with 2-dimensional center.