Multi-component Harry--Dym hierarchy and its integrable couplings as well as their Hamiltonian structures

This paper obtains the multi-component Harry--Dym (H--D) hierarchy and its integrable couplings by using two kinds of vector loop algebras \widetildeG_3 and \widetildeG_6. The Hamiltonian structures of the above system are given by the quadratic-form identity. The method can be used to produce the Hamiltonian structures of the other integrable couplings or multi-component hierarchies.