Symmetric functions and the centre of the Ringel-Hall algebra of a cyclic quiver

We obtain explicit generators for the centre of the Ringel-Hall algebra of a cyclic quiver and define a canonical algebra monomorphism from Macdonald's ring of symmetric functions to the centre, which furthermore respects the comultiplication and the symmetric bilinear form. Dedicated to Claus Michael Ringel on the occasion of his 60th birthday