claimroutine

Separated weights avoid center dependence

Chooses successive weights with ∏Awa>C∗∏Bvb\prod_A w_a>C_*\prod_B v_b, independent of the points
arithmetic weight separation used throughout the geometric proofs
Claim·§2.2 The curve inequality·inside thmInterpolation with separated weights

Statement (paper)

Fix a positive rational number σ\sigma satisfying , put vi=wi/θv_i=w_i/\theta for i>0i>0, L0=m+2L_0=m+2 and C∗=max⁡1≤k≤m2k!(L0/σ)kC_*=\max_{1\le k\le m}2k!(L_0/\sigma)^k. Then the positive weights w1,…,wmw_1,\ldots,w_m can be chosen successively, depending only on the fixed data m,K,w0,v0,θm,K,w_0,v_0,\theta and the previously chosen weights (and not on any interpolation point), so that for every pair of subsets A,B⊆{0,…,m}A,B\subseteq\{0,\ldots,m\} of the same cardinality between 11 and mm, ∏a∈Awa>C∗∏b∈Bvb\prod_{a\in A}w_a>C_*\prod_{b\in B}v_b whenever the largest positive index in their symmetric difference belongs to AA.

In plain English

Given a fixed rational σ\sigma satisfying , with vi=wi/θv_i=w_i/\theta, L0=m+2L_0=m+2 and C∗=max⁡1≤k≤m2k!(L0/σ)kC_*=\max_{1\le k\le m}2k!(L_0/\sigma)^k, the weights w1,…,wmw_1,\ldots,w_m can be chosen successively (depending only on m,K,w0,v0,θm,K,w_0,v_0,\theta and earlier weights, not on the points) so that ∏a∈Awa>C∗∏b∈Bvb\prod_{a\in A}w_a>C_*\prod_{b\in B}v_b for all equal-size subsets A,B⊆{0,…,m}A,B\subseteq\{0,\ldots,m\} of size between 11 and mm whenever the largest positive index in A△BA\triangle B lies in AA.

Why it's here

This is a purely arithmetic choice of weights, made by taking each new wiw_i large enough compared with the earlier ones. The resulting strict separation of weight products gives each normal-basis index set a dominant term, so the later curve-inequality arguments never depend on the interpolation points or on which center is involved.</br>
Classified routine:
This is a standard finite-dominance construction: choose each successive weight large enough that its appearance on the left dominates every relevant product of earlier weights. The choice depends only on fixed data and previously chosen weights, not on interpolation points.

Sources

PaperOpen
Section
§2.2 The curve inequality
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sections/interpolation.tex:180
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