AI Grimoire

Interpretability

Methods for reading a trained network rather than training a better one: sparse dictionaries over activations, causal interventions on the residual stream, and the circuit-level claims those techniques license.

Nine entries across four branches. Two are stubs and are marked as such — read them as open questions rather than answers.

Features

features/ ›

decomposing activations into things that can be named

05.1
Crosscodersstubpromising
Shared dictionaries fitted across layers or across model checkpoints.
O(L·d·m)
05.2
Feature Absorptionstubpromising
When one SAE latent swallows a more specific feature’s activation mass.
—
05.3
Sparse Autoencoderscommon
Overcomplete dictionary learning on activations for monosemantic features.
O(d·m)

Circuits

circuits/ ›

named mechanisms, traced end to end

05.4
Induction Headsstandard
A two-head circuit that completes [A][B]…[A] with [B]; the substrate of in-context learning.
O(L²)

Causal methods

causal/ ›

intervening on activations to find what carries the behaviour

05.5
Activation Patchingstandard
Causal intervention swapping activations between clean and corrupt runs.
O(L·n)
05.6
Attribution Patchingcommon
First-order approximation to patching via a single backward pass.
O(L·n)
05.7
Path Patchingcommon
Restrict the intervention to a single computational path between components.
O(L²·n)
05.8
Steering Vectorscommon
Add a direction to the residual stream at inference to shift behaviour.
O(L·d)

Probing

probing/ ›

reading a model with a simpler model, and its limits

05.9
Logit Lenscommon
Project intermediate residual states through the unembedding matrix.
O(d·V)