Suppose a physical process is modelled by a Markov chain with transition probability
on S 1 ∪ S 2, S 1 denoting the transient states and S 2 a set of absorbing states.
If v denotes the output distribution on S 2, the question arises as to what input distributions (of raw materials) on S 1 produce v. In this note we give an alternative to the formulation of Ray and Margo [2] and reduce the problem to one system of linear inequalities. An application to random walk is given and the equiprobability case examined in detail.