Liu, Michaud and Tegmark (2022) — ARXIV-2210.01117, ICLR 2023. Read as NOTE-282.

Key takeaways

  • Grokking is not confined to algorithmic data. Induced on MNIST (depth-3 width-200 MLP, AdamW, MSE on one-hot targets), on IMDb with an LSTM, and on QM9 with a GCNN. The signal is weaker than on algorithmic data in every case.
  • It takes two deliberate changes, and the paper says so. For MNIST: cut the training set from 60k to 1k, and multiply the Kaiming-uniform initial weights by α > 1. At α = 1 there is no grokking. For IMDb, α = 6 groks weakly and α = 1 does not; for QM9, α = 3.
  • And it can be removed. Constraining the model to a small-weight-norm sphere nearly eliminates grokking on algorithmic datasets.
  • The LU mechanism. Minimizing over angular directions at fixed norm, reduced training loss falls and then stays near zero — an “L” — while reduced test loss has a minimum at a critical norm w_c and rises on both sides — a “U”. Starting above w_c fits fast and generalizes only as regularization walks the norm back down. With weight decay γ, the training landscape becomes l̃_train(α) + γα²C².
  • The quantitative signature. In the teacher–student model at α = 2.0, time to 95% training accuracy is independent of γ, while time to 95% test accuracy is inversely proportional to γ. Small initializations (α = 0.5) generalize fast regardless.
  • Larger data de-groks by broadening the Goldilocks zone, and there is a critical training-set size below which generalization does not happen at all — reproducing Power et al.’s rapid rise in time-to-generalize on MNIST.
  • Why algorithmic data is dramatic: representation quality there decides between chance and 100%; on MNIST it decides between 95% and 100%.

Standing in the anthology

Active, and it is the paper that settles the scope question SOTA-200 was implicitly answering. The record said grokking is “a data-starved-regime phenomenon, not a fundamental one”, on one paper’s data-fraction result for modular addition. This one shows the regime has at least a second axis — where you start relative to the generalizing weight norm — and that setting both produces grokking on ordinary supervised tasks.

The LU mechanism itself is contested, by ARXIV-2310.06110’s counterexample in which the weight norm rises through grokking with no weight decay at all. That contest is over the mechanism, not over the induce-and-eliminate experiments, which nothing disputes.