Comment on `Boson-fermion model beyond the mean-field approximation'

In a recent paper, it has been suggested that there is no Cooper pairing in boson-fermion models of superconductivity. This result is based on an inconsistent approximation which violates an exact identity. Quite generally, the divergence of the fermion t-matrix (the Thouless criterion) is accompanied by the condensation of a boson mode.