← All parts of this equation

Equation 2 · Part 1 · What a Circuit Explains: The State and Limits of Mechanistic Interpretability

Symbol f

f(x)f(x)
ff

What this part means

f 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

f 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

Now the careful part. Consider what the training objective actually asks for. Writing x for an activation vector, f(x) for the sparse code and x^\hat{x} for the reconstruction, the objective has the form

Read this part in the article →

Learn the underlying idea

A function assigns an output to each allowed input. The expression f(x) means “apply f to x”.

Open the illustrated functions: inputs become outputs guide →

See this notation across published equations →

Sources cited in the article section

These citations provide research context; check each source for the exact claim it supports.