Classification of orbit closures in the variety of 4-dimensional symplectic Lie algebras

Abstract

The aim of this paper is to study the natural action of the real symplectic group, $\operatorname{Sp}(4, \mathbb{R})$, on the algebraic set of $4$-dimensional Lie algebras admitting symplectic structures and to give a complete classification of orbit closures. We present some applications of such classification to the study of the Ricci curvature of left-invariant almost K\"{a}hler structures on four dimensional Lie groups.