  We consider a Kondo spin that is coupled antiferromagnetically to a large
chaotic quantum dot. Such a dot is described by the so-called universal
Hamiltonian and its electrons are interacting via a ferromagnetic exchange
interaction. We derive an effective Hamiltonian in the limit of strong Kondo
coupling, where the screened Kondo spin effectively removes one electron from
the dot. We find that the exchange coupling constant in this reduced dot (with
one less electron) is renormalized and that new interaction terms appear beyond
the conventional terms of the strong-coupling limit. The eigenenergies of this
effective Hamiltonian are found to be in excellent agreement with exact
numerical results of the original model in the limit of strong Kondo coupling.
