证明
Lemma 5 ([Triangle normalization and peeling]). For a positive-weighted finite…Lemma 9. There is a choice of these labels for which the projection (u,y)↦u…Lemma 4 ([Preservation under splitting]). Let (G,w) satisfy with constant C .…观点
Peel edges whose current common-neighbor weight is less than 1/x . If H is the remaining graph, Lemma 5 ([Triangle normalization and peeling]) gives T_H(w)≥T_G(w)-M_G(w)/x. Edge deletion does not increase any weighted neighborhood, and it preserves the cross-mass condition. If H has no edges, take G' to be empty. Then T_G(w)≤M_G(w)/x , which implies . Otherwise, apply Lemma 9 to H . Since x↦ x/√x is decreasing for x≥e^2 , ensures 0≤1-a_C x/√x≤1 . Hence T_ G' (w) , ≥(1-a_C( x)/(√x)) (T_G(w)-M_G(w)x); , ≥(1-a_C( x)/(√x))T_G(w) -M_G(w)x. The projection through H is still injective on directed edges. The edge-mass bound and inherited cross-mass condition follow from Lemma 4 ([Preservation under splitting]).