Table 1 Procedure ReTrace

ReTrace (ℛ, S, T, w, k, l):

Input: reactions R, sources S, targets T, 0 <w ≤ 1 and k, l ∈ ℤ⁺

1:

G ← G(R)

2:

Add nodes v_Δ and v _U to G

3:

Add edges (v_Δ, v _s ) for each s ∈ S to G

4:

P ← ∅ % Current pathway

5:

U ← T % Unresolved nodes

6:

FindPath(G, P, v_Δ, U, w, k, l)