claimroutine

Row sup bounds convert to summed powers

Row sup bounds convert to summed ss-th powers at fixed factor
converts sup bounds into the summed-power norm
Claim·§8.4 Charging overflow events·inside propCompression preserves row error budget

Statement (paper)

Equation  converts every row sup bound into a bound for the summed output power with a fixed factor: the support of a discrepancy lies in the union of the true and computed supports, whose total size over H\mathcal H is at most 2Csupp2C_{\mathrm{supp}}, so this step introduces no factor from the ambient number of endpoints.

In plain English

A uniform bound on each row's discrepancy (the row support bound) yields a bound on the sum over H∈HH\in\mathcal H and yy of the discrepancy's ss-th power. This costs only a fixed factor, because a discrepancy is supported on the union of the true and computed supports, whose total size over H\mathcal H is at most 2Csupp2C_{\mathrm{supp}}.

Why it's here

This turns pointwise row sup bounds into the summed-power norm that the integrated error bound for the proposition uses. The conversion depends only on the support size 2Csupp2C_{\mathrm{supp}} and not on the ambient number of endpoints, so CbufC_{\mathrm{buf}} stays independent of the number of groups and row width. The later claims on preloss, no-overflow and overflow contributions use it to convert their sup bounds into summed powers.
Classified routine:
An elementary sup-to-sum bound: summing the s-th power of a function bounded pointwise over a support of size at most 2C_supp gives at most 2C_supp times the sup to the s-th power. It is bookkeeping inside the paper's own buffer-error argument.

Sources

PaperOpen
Section
§8.4 Charging overflow events
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sections/compression.tex:485
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