Graphical representation of the first value in the definition of score, for the case q = ℱ, assuming c(i) = P_≥(j) = ℓ and a_i further has children b_{ℓ +1} and b_{ℓ +2}. Because q = ℱ, there was some other node b_ℓ′ in the same component that was shifted on to the stack earlier and given a (non-gold) parent; let us assume ℓ′ = ℓ − 1. We can add 3 children to the score, but should subtract Δ(c(i) = P ≥ (j) ∧ q ≠ 𝒩) = 1, to compensate for the fact that edge (b_ℓ,b_ℓ−1) cannot be constructed, as b_ℓ−1 can only have one parent. If we further assume a_i has a parent among the critical nodes, then that parent must be in a different component, and therefore τ (i, j, q) = 𝒩.