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Published equation contexts

y^(x)=σ(w⊤hℓ(x)+b)\hat y(x) = \sigma\big(w^\top h_\ell(x) + b\big)

Why this formula appears here

Formally, a probe is a function fitted independently of the network under study: y^(x)=σ(w⊤hℓ(x)+b)\hat y(x) = \sigma\big(w^\top h_\ell(x) + b\big). 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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Published contexts (1)

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y^(x)=σ(w⊤hℓ(x)+b),\hat y(x) = \sigma\big(w^\top h_\ell(x) + b\big),

Equation 1 · AI Research

Probing, Sparse Autoencoders, Patching, and Steering: The Main Interpretability Methods, Compared

This equation states an equality: the expressions on both sides have the same value under the article’s assumptions.

Formally, a probe is a function fitted independently of the network under study: y^(x)=σ(w⊤hℓ(x)+b)\hat y(x) = \sigma\big(w^\top h_\ell(x) + b\big). 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.

Meanings in this article

  • hℓh_\ell: the frozen activation the network produces at layer ℓ\ell for input x , and w.
  • bb: the probe’s own parameters, trained on labelled examples the network never saw during its own training.
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