13 week Mech Interp Study Journal


Mech Interp is super cool! I’m gonna set aside 13 weeks to study it. In these 13 weeks, I plan to master basic ML math, master transformers, read a couple mech interp papers in depth, and hopefully carry out some small-scaled, original mech interp exploration.

Note, this is a direct mirror of my personal log in my Obsidian vault, and some formatting might not be appropriate (I will format everything at the end).


Target: 10/28/2023 to 1/26/2023 (end of my winter break)

Undated Day 1

  • Read some basic definitions of Linear Algebra Done Right.

    Undated Day 2

  • Finished Linear Algebra Done Right Chapter 1. Re-learnt subspaces, sums of subspaces, direct sums.
  • Looking ahead, to solidfy my linear algebra for MI, I should master Chapter 1-3, 5-6, and 7d. More importantly, I need to spend some time everyday in finding connections of the niche linear algebra techniques are used for ML.
  • I found one such connection today (querying ChatGPT): Gradients should be initialized with orthonormal matrices in order to preserve the magnitude of gradients.

Day 1

  • Read Linear Algebra Done Right Chapter 2 up until the last definition. I think basis and theorems regarding bases drilled in the definition of linear independence and span.
  • Tomorrow, I just want to finish up the definition, do a few problems. Then, I want to skim some high-level material on why bases matters for machine learning; in particular, I hear a lot about “orthonormal” bases in ML, when and why do they come up?
  • Why bases matter for machine learning - high level view. 📅 2023-10-28 ✅ 2023-10-28

Day 2

  • Yesterday i assigned the “why bases matters” task, I have a high-level answer: To address the curse of dimensionality and other dimension related issues. Keywords are privileged, non-privileged bases, PCA, SVD.
    • Resources: https://harrisonpim.com/blog/privileged-vs-non-privileged-bases-in-machine-learning

Day 3


Day 4

  • Did 15 exercises for [[Chapter 2]]. I didn’t try too hard, I looked at the solution if I can’t solve in 5 mins.

Day 5


Day 6


Day 7 (11-03-2023)

Wrote MLP forward stuff.

Watched this great video by WhyML on Skip connection and residual blocks.

  • Review Batch Normaliztaion, Optimizers, Regularization, Gradient Clipping, Weight Constraints, Weight Normalization, Layer Normalization 📅 2023-11-04 ✅ 2023-11-09
  • What is Skip Connections and Residual Blocks? 📅 2023-11-03 ✅ 2023-11-04
  • Understand the gradients that are taken. 📅 2023-11-12 ✅ 2023-11-15

Day 8 (11-04-2023)

Studied backpropagation. I used multiple resources: The original sparse encoder article, some random article by ML-dawn, and Brilliant Wiki. But, when I revisited 3b1b’s video, that’s the one that made it all click. Tomorrow, I plan to rewatch the video and take a lot of notes.

Day 9 (11-05-2023)

Rewatched 3b1b’s video and I think all the formulae individually makes sense. Tomorrow, I’ll try to

  • Derive the gradients from scratch
  • If I get them right, give a shot at drawing derivative diagrams for a MLP
  • Implement backprop in MLP.

Day 10-18 (11-06-2023 to 11-14-2023)

Skipped. Not gonna lie, played a little too much minesweeper.

Day 19

  • Deleted my online minesweeper account. Started 2 weeks ago and sunk 35 hours into it, no good, those hours will now be redirected to mech interp.
  • Watched Neel Nanda’s MI and Math talk and annotated it. The slides are here
  • 40 mins into ML street talk episode with Neel Nanda. Take aways:
    • A biologist’s getting hands dirty view might be more appropriate than a mathematician’s view. A good quality of a mech interp researcher is someone who can handle a surprise.

My goals this week is to start understanding transformers well, read this paper, and get a sense of the other techniques I gotta study (dimensionality reduction, Fourier transform even?).

Idea: Analyze transformers that implement simple regexes / text manipulation patterns?

Day 20

Some knowledge tasks.

  • Understand: What is the Curse of Dimensionality? 📅 2023-11-17
  • Master PCA 📅 2023-11-19

Inspired by Neel’s talks yesterday, I will run a mech interp notebook this week to get a feel of the tools.

  • Run, completely, one mech interp notebook 📅 2023-11-17