Timeline for When is the Levi subalgebra an ideal?

12 events

when toggle format	what		by	license	comment
Apr 18, 2011 at 12:31	vote	accept	user14312
Apr 18, 2011 at 11:12	answer	added	Jim Humphreys		timeline score: 6
Apr 18, 2011 at 5:22	vote	accept	user14312
Apr 18, 2011 at 12:31
Apr 18, 2011 at 5:10	answer	added	Ben Webster♦		timeline score: 3
Apr 18, 2011 at 4:58	history	edited	user14312	CC BY-SA 3.0	added 96 characters in body
Apr 18, 2011 at 4:49	history	edited	user14312	CC BY-SA 3.0	added 60 characters in body
Apr 18, 2011 at 4:45	comment	added	user14312		I will edit the question.
Apr 18, 2011 at 4:44	comment	added	user14312		As direct sum I mean direct sum of vector subspaces, not submodules.
Apr 18, 2011 at 4:43	comment	added	Kevin Ventullo		The answer is no. For instance, if $L$ is a non-abelian solvable Lie algebra, then $S=0$ is certainly an ideal, but $L=rad(L)\neq Z(L)$.
Apr 18, 2011 at 4:36	comment	added	Ben Webster♦		I'm not sure what the question here is. S is an ideal if and only if L is the direct sum of S and rad(L); this is essentially the definition of "direct sum."
Apr 18, 2011 at 4:13	history	edited	user14312	CC BY-SA 3.0	added 2 characters in body
Apr 18, 2011 at 3:41	history	asked	user14312	CC BY-SA 3.0