  A binary matrix is called an s-separable code for the disjunctive
multiple-access channel (disj-MAC) if Boolean sums of sets of s columns are all
distinct. The well-known issue of the combinatorial coding theory is to obtain
upper and lower bounds on the rate of s-separable codes for disj-MAC. In our
paper, we generalize the problem and discuss upper and lower bounds on the rate
of q-ary s-separable codes for models of noiseless symmetric MAC, i.e., when at
each time instant the output signal of MAC is a symmetric function of its s
input signals.
