We describe an algebra G of diagrams which faithfully gives a diagrammatic
representation of the structures of both the Heisenberg-Weyl algebra H - the
associative algebra of the creation and annihilation operators of quantum
mechanics - and U(L_H), the enveloping algebra of the Heisenberg Lie algebra
L_H. We show explicitly how G may be endowed with the structure of a Hopf
algebra, which is also mirrored in the structure of U(L_H).
This paper provides motivation as well as a method of construction for Hopf
algebras, starting from an associative algebra. The dualization technique
involved relies heavily on the use of Sweedler's dual.
We construct explicit solutions of a number of Stieltjes moment problems
based on moments of the form ${\rho}_{1}^{(r)}(n)=(2rn)!$ and
${\rho}_{2}^{(r)}(n)=[(rn)!]^{2}$, $r=1,2,...$, $n=0,1,2,...$, \textit{i.e.} we
find functions $W^{(r)}_{1,2}(x)>0$ satisfying
$\int_{0}^{\infty}x^{n}W^{(r)}_{1,2}(x)dx = {\rho}_{1,2}^{(r)}(n)$. It is shown
using criteria for uniqueness and non-uniqueness (Carleman, Krein, Berg, Pakes,
Stoyanov) that for $r>1$ both ${\rho}_{1,2}^{(r)}(n)$ give rise to non-unique
solutions.