Abstract: The Hausdorff matrices were introduced in the study of summability methods,
and can be characterized as those matrices that commute with the Cesaro
matrix C. Using Hilbert space techniques, one can define a functional
calculus that represent the Hausdorff matrices defining continuous operators
on ell_2 as operators g(C), where
g is a bounded analytic function in the interior of the spectrum of C.
The aim of this talk is to describe this representation, and to comment on
the problems that one finds to extend the representation to other values of