2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/174690Let $g$ be a classical Lie algebra, i.e., either $gl_n$, $sp_n$, or $so_n$ and let $e\in g$ be a nilpotent element. We study various properties of centralisers $g_e$. The first four sections deal with rather elementary questions, like the centre of $g_e$, commuting varieties associated with $g_e$, or centralisers of commuting pairs. The second half of the paper addresses problems related to different Poisson structures on $g_e^*$ and symmetric invariants of $g_e$.Final version, to appear in Ann. Inst. Fourier (Grenoble), v. 59 (2009)Representation Theorytext