Semi-inclusive deep inelastic lepton scattering off complex nuclei

It is shown that in semi-inclusive deep inelastic scattering (DIS) of elect rons off complex nuclei, the detection, in coincidence with the scattered e lectron, of a nucleus (A - 1) in the ground state, as well as of a nucleon and a nucleus (A - 2), also in the ground state, may provide unique informa tion on several long standing problems, such as: i) the nature and the rele vance of the final state interaction in DTS; ii) the validity of the specta tor mechanism in DIS; iii) the medium induced modifications of the nucleon structure function; iv) the origin of the EMC effect.