claimroutine

Precision choice beats coordinate factor N

Precision p=O(B)p=O(B) makes Pr⁡[∣WˉL−WL∣>Δ/8]≤1/8\Pr[|\bar W_L-W_L|>\Delta/8]\le1/8 at the start
absorbs the conditioning factor NN into the precision
Claim·§12.2 A dyadic approximation at the specified start·inside thmDeterministic logspace approximation of acceptance probability

Statement (paper)

With a=u=f=bLa=u=f=b_L and the fixed linear coefficient of Mtop=O(B)M_{\rm top}=O(B) chosen large enough that p≥r+3+CNB+⌈log⁡2Ctail⌉+38p\ge r+3+\frac{C_NB+\lceil\log_2 C_{\rm tail}\rceil+3}{8}, one has Pr⁡[∣WˉL(z)−WL(z)∣>Δ/8∣Xf(z)=1]≤1/8\Pr\bigl[|\bar W_L(z)-W_L(z)|>\Delta/8\mid X_f(z)=1\bigr]\le 1/8; in particular the bound in Equation  is at most Ctail 2CNB−8p+8r+24≤2−3C_{\rm tail}\,2^{C_NB-8p+8r+24}\le 2^{-3}.

In plain English

With the linear coefficient of Mtop=O(B)M_{\rm top}=O(B) large enough that p≥r+3+CNB+⌈log⁡2Ctail⌉+38p\ge r+3+\frac{C_NB+\lceil\log_2 C_{\rm tail}\rceil+3}{8}, the conditional probability that ∣WˉL(z)−WL(z)∣>Δ/8|\bar W_L(z)-W_L(z)|>\Delta/8 given Xf(z)=1X_f(z)=1 is at most 1/81/8. The tail bound is at most Ctail 2CNB−8p+8r+24≤2−3C_{\rm tail}\,2^{C_NB-8p+8r+24}\le 2^{-3}.

Why it's here

This applies the conditional eighth-moment bound at the specified start zz with the error bound from the fixed-precision estimators. The conditioning cost, a factor NN that is exponential in BB, is absorbed by choosing the precision pp larger by an amount linear in BB. That makes the failure probability at zz at most 1/81/8, which the next claim uses to read off accurate dyadic digits of WˉL(z)\bar W_L(z).
Classified routine:
Direct parameter bookkeeping: combines the conditional eighth-moment bound (lem-final-majority) with the estimator error bound (thm-fp-estimators) via Markov's inequality, absorbing the exponential-in-B conditioning factor by choosing the precision larger by an amount linear in B.

Sources

PaperOpen
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§12.2 A dyadic approximation at the specified start
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