claimroutineinferred_dep

Axis maps contract with error dp^2

Axis maps contract; dd axes give error <dp2<dp^2
carries 1D error and cost bounds to dd axes
Claim·§8.2 Growing dimension and the padded array·inside lemTensor resampling across d dimensions

Statement (paper)

Each axis map, which acts independently on its valid lines and is zero on the other lines, is a contraction and has error less than p2p^2. Hence the composition of the dd axis maps is a contraction with error less than dp2dp^2. For axis ii at most T/tiT/t_i lines invoke the one-dimensional algorithm, so the total time in the one-dimensional algorithms is ∑i=1dTtiO(tip3/2+δα)=O(dTp3/2+δα)\sum_{i=1}^d \frac{T}{t_i}O(t_i p^{3/2+\delta}\alpha)=O(dTp^{3/2+\delta}\alpha).

In plain English

Each axis map, which applies the one-dimensional approximation on valid lines and gives zero on other lines, is a contraction with error below p2p^2. Composing the dd axis maps gives a contraction with error below dp2dp^2, and the one-dimensional algorithms take total time O(dTp3/2+δα)O(dTp^{3/2+\delta}\alpha).

Why it's here

This turns the one-dimensional bounds of the no-sort resampling lemma into the contraction, error dp2dp^2 and time claims for A\mathcal A and B0\mathcal B_0 in the tensor lemma. Lines act independently, so contraction and the p2p^2 error carry over from one axis to the next and the errors add up over dd axes. For axis ii at most T/tiT/t_i lines call the one-dimensional algorithm at cost O(tip3/2+δα)O(t_ip^{3/2+\delta}\alpha) each, so each axis costs O(Tp3/2+δα)O(Tp^{3/2+\delta}\alpha) and the sum over dd axes gives the stated total.
Classified routine:
Direct bookkeeping consequence of the one-dimensional no-sort resampling lemma. Contractions compose, errors add under composition of contractions, and the per-axis time is summed over lines and axes.

Sources

PaperOpen
Section
§8.2 Growing dimension and the padded array
Page
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Label
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Line
sections/07-resampling.tex:362
Leannot aligned

Phase 2 aligns this node to a Lean declaration.

Friction

  • info
    inferred_dep
    outline: "Axis maps contract; error dp^2 and line cost" rests on claim-lem-tensor-resampling-1
  • info
    inferred_dep
    outline: "Axis maps contract; error dp^2 and line cost" rests on lem:no-sort-resampling