We show that the Hopf algebra dual of the polynomials in one variable
appears often in analysis, but under different disguises that include
proper rational functions, exponential polynomials, shift invariant op
erators, Taylor functionals, and linearly recurrent sequences. The iso
morphisms from the proper rational functions to the other algebras yie
ld an explicit and general method for the solution of linear functiona
l equations, which can be considered as an algebraic version of the us
ual integral transform methods. We also explain how some of the usual
convolution products in spaces of functions arise in an algebraic way.
(C) 1997 Academic Press.