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Equation 2 · Part 1 · What Interpretability Actually Costs to Do at Scale

Symbol n

nn
nn

What this part means

n is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Its job in the formula

n is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

The passage around this formula

A sparse autoencoder (SAE) is trained to reconstruct a model’s internal activation vectors through a sparse bottleneck: an encoder maps an activation of dimension d into a much wider space of n candidate “features,” a sparsity constraint keeps only k of those features active per token, and a decoder reconstructs the original activation from just those k . The training objective, in its standard form, is

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Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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Sources cited in the article section

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