  We investigate maximal exceptional sequences of line bundles on (P^1)^3, i.e.
those consisting of 2^r elements. For r=3 we show that they are always full,
meaning that they generate the derived category. Everything is done in the
discrete setup: Exceptional sequences of line bundles appear as special finite
subsets s of the Picard group Z^r of (P^1)^r, and the question of generation is
understood like a process of contamination of the whole Z^r out of an
infectious seed s.
