lemmaroutine

Atom correction is exact with bounded gate

Correction atom has exact conditional mean F(x,y)F(x,y) and normalization ≥ 3/4
unbiasedness of the correction estimator
Lemma·lem:atom-correction·§5.3 Corrections with an incoming gate

Statement (paper)

For sufficiently large fixed KK and then KcK_c, the conditional mean of fF(x,y)f\mathcal F(x,y) on Xu(x)=Yt(y)=1X_u(x)=Y_t(y)=1 is exactly F(x,y)F(x,y). On a true position with Q(dy)>0Q(d_y)>0 and g0(y)>0g_0(y)>0, qy=α(x,y):=E[RTy∣Xu(x)=Yt(y)=1]≥3/4. q_y=\alpha(x,y):= \mathbb E[R T_y\mid X_u(x)=Y_t(y)=1]\ge3/4. No lower bound on qyq_y or α(x,y)\alpha(x,y) is required when g0(y)=0g_0(y)=0. The true gates and normalization use only the two role channels X,YX,Y; g0g_0 is deterministic.

In plain English

For sufficiently large fixed KK and then KcK_c, the conditional mean of fF(x,y)f\mathcal F(x,y) given Xu(x)=Yt(y)=1X_u(x)=Y_t(y)=1 equals F(x,y)F(x,y) exactly. On a true position with Q(dy)>0Q(d_y)>0 and g0(y)>0g_0(y)>0, the normalization qy=α(x,y)=E[RTy∣Xu(x)=Yt(y)=1]q_y=\alpha(x,y)=\mathbb E[R T_y\mid X_u(x)=Y_t(y)=1] is at least 3/43/4, and no lower bound is needed when g0(y)=0g_0(y)=0.

Why it's here

This shows the correction built on the dense-bin atom table is unbiased on the slice, building on the atom identity of the dense-bin lemma. The lower bound qy≥3/4q_y\ge 3/4 keeps the normalization away from zero on positions where the incoming gate is active. The true gates and normalization depend only on the two role channels X,YX,Y, and g0g_0 is deterministic, so the correction uses no extra randomness.
Classified routine:
A direct consequence of the dense-bin atom identity (lem-atom-dense): unbiasedness on the slice follows from normalizing by the conditional mean, and the bound q_y ≥ 3/4 comes from taking the constants K and K_c large. This is parameter bookkeeping on top of the earlier lemma, not a new idea.

Uses

Used by

Nothing in the paper

Sources

PaperOpen
Section
§5.3 Corrections with an incoming gate
Page
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Label
lem:atom-correction
Line
sections/atoms.tex:335
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