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Equation 12 · How Fast Can a Horizon Learn Which Path You Took?

What does this equation mean?

h2(p)=−plog⁡2p−(1−p)log⁡2(1−p)h_2(p)=-p\log_2p-(1-p)\log_2(1-p)

Read the formula alongside the article passage below. Each part has a deeper page with its role in the equation, the supporting passage and nearby citations.

Inputs and operations-plog_2p-(1-p)log_2(1-p)
Result or conditionh_2(p)
How to read the two sides of this formula. Follow the article passage for the meaning of each quantity.

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.

Read it piece by piece

h2h_2

Symbol h_2

h2h_2 is part of the quantity the equation computes from the expression on the right.

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pp

Symbol p

p 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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=

=

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

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subtraction

subtraction

Subtract the following term or group from the preceding one. A leading minus marks a negative quantity.

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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

Read it with the definitions, units, and assumptions supplied by the article.

What the article says around this equation

where h2(p)=−plog⁡2p−(1−p)log⁡2(1−p)h_2(p)=-p\log_2p-(1-p)\log_2(1-p). is binary entropy. The first equation inherits quantum minimum-error detection [ 14 ] . The second is ordinary mutual information for the resulting binary channel. It answers a concrete question: if one path bit was chosen fairly and one optimized single-shot yes/no measurement was made, how many bits did that decision convey on average?

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Sources cited in the surrounding passage

These citations give research context. Read each source to check which claims it supports.

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