“…where x t ∈ R + is a non-negative system state, whose initial conditions belong to a given interval x 0 ∈ [x 0 , x 0 ], a t ∈ R + and d t ∈ R are uncertain inputs, which also take values in known intervals a t ∈ [a t , a t ], d t ∈ [d t , d t ], for all t ∈ N. So, we assume that x 0 ≤ x 0 , 0 ≤ a t ≤ a t and d t ≤ d t are known for all t ∈ N. The imposed non-negativity constraints on x t and a t correspond to the case of the model (1). We wish to calculate the lower x t and upper x t predictions on the state x t of this system under the introduced hypotheses on all uncertain variables, which have to satisfy x t ≤ x t ≤ x t , ∀t ∈ N. The theory of interval observers and predictors [17], [22] answers this question, and a possible solution (that utilizes the non-negativity of x t and a t ) is as follows:…”