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Equation 5 · Part 2 · Probing, Sparse Autoencoders, Patching, and Steering: The Main Interpretability Methods, Compared

Symbol b

w,bw, b
bb

What this part means

the probe’s own parameters, trained on labelled examples the network never saw during its own training.

Its job in the formula

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

Where the article explains it

where hℓ(x)h_\ell(x) is the frozen activation the network produces at layer ℓ\ell for input x , and w, b are the probe’s own parameters, trained on labelled examples the network never saw during its own training.

The passage around this formula

where hℓ(x)h_\ell(x) is the frozen activation the network produces at layer ℓ\ell for input x , and w, b are the probe’s own parameters, trained on labelled examples the network never saw during its own training. Nothing in that objective touches the network’s weights or its downstream computation. A probe reports only whether some linear function of this one activation predicts the label well.

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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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