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Mar 7, 2015 at 10:55 comment added YCor Anyway I'm puzzled by your question when you say "similar to the Euclidean case": even if $g_1,g_2$ are abelian of the same dimension, you don't have any canonical definition of determinant for a linear mapping $g_1\to g_2$. You need to fix some element in the maximal exterior power of each $g_i$ (which is 1-dimensional) in order to normalize.
Mar 2, 2015 at 13:14 comment added Changyu Guo @YCor:In particular, such a Lie algebra admit a group operation * by the BCH formula so that g, with *, becomes a Carnot group of homogenuous dimension $Q=\sum_{i=1}^s i\dim V_i$.
Mar 2, 2015 at 13:09 comment added Changyu Guo @YCor: I am sorry that I do not know there are many different notions of this concept. I followed the lecture notes by Enrico, which can be found here sites.google.com/site/enricoledonne/lecture_notes, the stratification of step $s$ means that $g=V_1\oplus V_2\cdots\oplus V_s$, with $[V_j,V_1]=V_{j+1}$ for $1\leq j\leq s-1$ and $V_s\neq \{0\}$.
Mar 2, 2015 at 9:33 comment added YCor Could you provide your definition of stratified/graded Lie algebras? graded in positive integers? even in this context, there are many different non-equivalent definitions, especially some people make the requirement that the elements of degree 1 generate the Lie algebra.
Mar 2, 2015 at 7:35 history asked Changyu Guo CC BY-SA 3.0