where f k (uv) := τ k,u τ k,v , E n,1 are the edges that are added as we advance from step n -1 to n and E n,2 are the edges that modify their τ u τ v as we advance from step n -1 to n. If we focus on each sum individually, it turns out that for n ≥ 6, uv∈En,1