  We discuss the adequate treatment of the 3- and 4-body dynamics for the quark
model picture of double-charm baryons and tetraquarks. We stress that the
variational and Born-Oppenheimer approximations give energies very close to the
exact ones, while the diquark approximation might be rather misleading. The
Hall-Post inequalities also provide very useful lower bounds that exclude the
possibility of stable tetraquarks for some mass ratios and some color wave
functions.
