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Equation 44 · How Fast Can a Horizon Learn Which Path You Took?

What does this equation mean?

Treceipt(δ)=inf⁡{tc:Iirr(tc)≥1−δ}.T_{\rm receipt}(\delta)= \inf\{t_c:I_{\rm irr}(t_c)\geq1-\delta\}.

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Inputs and operationsinft_c:I_rm irr(t_c) ≥ 1-delta
Result or conditionT_rm receipt(delta)
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This equation states an equality: the expressions on both sides have the same value under the article’s assumptions. Read the equation part by part below; each part has a contextual explanation and a link to its mathematical background.

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TreceiptT_{\rm receipt}

Symbol T_rm receipt

TrT_rm receipt is part of the quantity the equation computes from the expression on the right.

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δ\delta

Symbol delta

delta is an argument of the function-like quantity on the left; its role is set by that function’s stated inputs.

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tct_c

Symbol t_c

the become irrevocable at an intermediate cutoff.

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IirrI_{\rm irr}

Symbol I_rm irr

IrI_rm irr is one of the signed contributions combined to compute the quantity on the left.

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=

=

The expressions on both sides represent the same quantity under the stated assumptions.

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subscript

subscript

The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.

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How to interpret it

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What the article says around this equation

Finally, the proposed horizon receipt time is Treceipt(δ)=inf⁡{tc:Iirr(tc)≥1−δ}T_{\rm receipt}(\delta)= \inf\{t_c:I_{\rm irr}(t_c)\geq1-\delta\}. These are proposed definitions, not results from the 2025 optimization paper. They deliberately make admissible control part of the quantity. If A\mathcal A grants arbitrary global unitaries on the horizon, the record can become fictitiously erasable. If it permits only “do nothing,” receipt time collapses into an ordinary decay threshold. A physically useful answer must live between those caricatures.

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