  The occurrence of retarded (with glue) and unretarded (without glue) pairing
is thoroughly discussed in cuprates. We analyze some aspects of this problem in
the context of the t-J-V model in a large-N approximation. When 1/N
renormalizations are neglected the mean-field result is recovered, where the
unretarded d-wave superconducting pairing triggered by the spin-exchange
interaction J is obtained. However, the presence of a non-negligible
nearest-neighbors Coulomb interaction V(q) kills superconductivity. If the
non-double-occupancy constraint and its fluctuations are considered, the
situation changes drastically. In this case, V(q) is screened making d-wave
superconductivity very robust. In addition, we show that the early proposal for
the presence of an unretarded pairing contribution triggered by the
spin-exchange interaction J can be discussed in this context.
