  We study the role played by the dilution in the average behavior of a
perceptron model with continuous coupling with the replica method. We analyze
the stability of the replica symmetric solution as a function of the dilution
field for the generalization and memorization problems. Thanks to a Gardner
like stability analysis we show that at any fixed ratio $\alpha$ between the
number of patterns M and the dimension N of the perceptron ($\alpha=M/N$),
there exists a critical dilution field $h_c$ above which the replica symmetric
ansatz becomes unstable.
