The universal enveloping algebra, Li(g), of a Lie algebra B supports s
ome norms and seminorms that have arisen naturally in the context of h
eat kernel analysis on Lie groups. These norms and seminorms are inves
tigated here from an algebraic viewpoint. It is shown that the norms c
orresponding to heat kernels on the associated Lie groups decompose as
product norms under the natural isomorphism U(g(1) + g(2)) congruent
to U(g(1)) x U(g(2)) The seminorms corresponding to Green's functions
are examined at a purely Lie algebra level for s1(2, C). It is also sh
own that the algebraic dual space U' is spanned by its finite rank ele
ments if and only if fl is nilpotent.