Before revision:  We also investigate the role of ageing, thought of as a progressive increase in the degree of correlation (specificity) , and we show that it can possibly induce mild percolation phenomena, which are investigated too.
After revision:  We also investigate the role of ageing, thought of as a progressive increase in the degree of bias in bit-strings , and we show that it can possibly induce mild percolation phenomena, which are investigated too.