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Published equation contexts

di(m2)≈∑j=1m1gj dj(m1),∥g∥0≪m1,m1<m2d_i^{(m_2)} \approx \sum_{j=1}^{m_1} g_j\, d_j^{(m_1)}, \qquad \lVert g \rVert_0 \ll m_1, \quad m_1 < m_2

Why this formula appears here

Leask, Nanda and colleagues then tested the assumption directly with two new techniques, and the result undercuts the idea that there is a “right” dictionary size waiting to be found by scaling further. Stitching the dictionaries of differently sized sparse autoencoders together, they show that larger dictionaries recover latents genuinely missing from smaller ones — the smaller dictionary is incomplete. Training a second, “meta” sparse autoencoder on the decoder directions of a first one, they show that what looks like a single, atomic feature in a large dictionary is itself well approximated by a sparse combination of directions from a smaller one — a reported example decomposes an…

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di(m2)d_i^{(m_2)}

Symbol d_i^(m_2)

d_i^(m2m_2) is part of the quantity the equation computes from the expression on the right.

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jj

Symbol j

j appears in the bound of this sum. The bound states where the repeated operation starts, ends, or which values it includes.

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m1m_1

Symbol m_1

m1m_1 appears in the bound of this sum. The bound states where the repeated operation starts, ends, or which values it includes.

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dj(m1)d_j^{(m_1)}

Symbol d_j^(m_1)

d_j^(m1m_1) is an input to the expression that computes the quantity on the left.

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m2m_2

Symbol m_2

m2m_2 is an argument of the function-like quantity on the left; its role is set by that function’s stated inputs.

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j=1j=1

Starting index or lower bound: j=1

This label says where the repeated addition, multiplication, or accumulation starts. Read its value or condition together with the article’s description of the index.

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m1m_1

Ending index or upper bound: m_1

This label says where the repeated addition, multiplication, or accumulation stops. It sets the last term or end of the range.

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How to interpret it

Its accuracy depends on the assumptions and range of use described in the article. Read it with the definitions, units, and assumptions supplied by the article.

Research cited beside this formula

Published contexts (1)

A symbol can carry a different meaning in another article. Each occurrence keeps its own guide and term definitions.

di(m2)≈∑j=1m1gj dj(m1),∥g∥0≪m1,m1<m2,d_i^{(m_2)} \approx \sum_{j=1}^{m_1} g_j\, d_j^{(m_1)}, \qquad \lVert g \rVert_0 \ll m_1, \quad m_1 < m_2,

Equation 5 · AI Research

The Hardest Unsolved Problems in Mechanistic Interpretability

This equation gives an approximation: it relates the quantities while allowing an approximation.

Leask, Nanda and colleagues then tested the assumption directly with two new techniques, and the result undercuts the idea that there is a “right” dictionary size waiting to be found by scaling further. Stitching the dictionaries of differently sized sparse autoencoders together, they show that larger dictionaries recover latents genuinely missing from smaller ones — the smaller dictionary is incomplete. Training a second, “meta” sparse autoencoder on the decoder directions of a first one, they show that what looks like a single, atomic feature in a large dictionary is itself well approximated by a sparse combination of directions from a smaller one — a reported example decomposes an…

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