Jesse Hoogland

Executive director at Timaeus. Working on singular learning theory and developmental interpretability.

Website: jessehoogland.com

Twitter: @jesse_hoogland

Sequences

Developmental Interpretability
The Shallow Reality of 'Deep Learning Theory'

Wiki Contributions

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We're not currently hiring, but you can always send us a CV to be kept in the loop and notified of next rounds.

East wrong is least wrong. Nuke ‘em dead generals!

Reply72111

To be clear, I don't care about the particular courses, I care about the skills. 

This has been fixed, thanks.

I'd like to point out that for neural networks, isolated critical points (whether minima, maxima, or saddle points) basically do not exist. Instead, it's valleys and ridges all the way down. So the word "basin" (which suggests the geometry is parabolic) is misleading. 

Because critical points are non-isolated, there are more important kinds of "flatness" than having small second derivatives. Neural networks have degenerate loss landscapes: their Hessians have zero-valued eigenvalues, which means there are directions you can walk along that don't change the loss (or that change the loss by a cubic or higher power rather than a quadratic power). The dominant contribution to how volume scales in the loss landscape comes from the behavior of the loss in those degenerate directions. This is much more significant than the behavior of the quadratic directions. The amount of degeneracy is quantified by singular learning theory's local learning coefficient (LLC)

In the Bayesian setting, the relationship between geometric degeneracy and inductive biases is well understood through Watanabe's free energy formula. There's an inductive bias towards more degenerate parts of parameter space that's especially strong earlier in the learning process.

Anecdotally (I couldn't find confirmation after a few minutes of searching), I remember hearing a claim about Darwin being particularly ahead of the curve with sexual selection & mate choice. That without Darwin it might have taken decades for biologists to come to the same realizations. 

Answer by Jesse Hoogland224

If you'll allow linguistics, Pāṇini was two and a half thousand years ahead of modern descriptive linguists.

Right. SLT tells us how to operationalize and measure (via the LLC) basin volume in general for DL. It tells us about the relation between the LLC and meaningful inductive biases in the particular setting described in this post. I expect future SLT to give us meaningful predictions about inductive biases in DL in particular. 

If we actually had the precision and maturity of understanding to predict this "volume" question, we'd probably (but not definitely) be able to make fundamental contributions to DL generalization theory + inductive bias research. 

 

Obligatory singular learning theory plug: SLT can and does make predictions about the "volume" question. There will be a post soon by @Daniel Murfet that provides a clear example of this. 

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