Figure 2

Improving the tree topology. The subtrees T₁ and T₂ are reconnected by an edge from s to v₂, where s ∈ Cloud(v₁, ${v^{\prime }}_1$) and v₂ ∈ V₂. The edge (v₁, ${v^{\prime }}_1$) must be split into two edges (v₁, s) and (s, ${v^{\prime }}_1$) before the new edge (s, v₂) is added. Clouds are removed/generated accordingly.