Circuit Synchronization Precedes Generalization: Fourier Structure in Grokking Transformers
arXiv preprintIntroduces the Frequency Synchronization Degree (FSD) — a permutation-tested metric for Fourier circuit synchronisation that requires no prior circuit knowledge. FSD predicts grokking 500–3,000 steps in advance across nine modular-addition configs (mean lead +1,722 steps). Weight-decay intervention at the FSD ceiling causally confirms Phase 2 is regularisation, not computation: ∆t ∝ 1/λ across three primes.