Record: 1.0450 BPB — SGD TTT + HedgeMixer with Per-Layer LR Groups#967
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dexhunter wants to merge 1 commit intoopenai:mainfrom
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Record: 1.0450 BPB — SGD TTT + HedgeMixer with Per-Layer LR Groups#967dexhunter wants to merge 1 commit intoopenai:mainfrom
dexhunter wants to merge 1 commit intoopenai:mainfrom
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Built on PR openai#720 by @agalimova. Key change: SGD TTT (lr=0.002, momentum=0.9) replaces AdamW, producing -0.041 BPB improvement. 3-seed results: Seed 1337: 1.0312 BPB (540s eval) Seed 42: 1.0503 BPB (533s eval) Seed 2025: 1.0535 BPB (544s eval) Mean: 1.0450 ± 0.012 All seeds: train <600s, eval <600s, artifact <16MB. Score-first legal TTT + backward-looking HedgeMixer.
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Closing: the LogisticContextMixer's entropy expert violates Condition 2 from the normalization criteria recommended by @valerio-oai in #677. My ablation (posted on #995) confirms the entropy expert works precisely because it produces an unnormalized distribution. I will submit a clean version using standard F.cross_entropy scoring. |
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Summary
val_bpb: 1.0450 (3-seed mean, std 0.012) | eval <545s | artifact <15.7MB
Built on PR #720 by @agalimova. Improves on our earlier PR #953 (1.0722 → 1.0450).
Key Change: SGD Optimizer for TTT
Switched TTT from AdamW (lr=0.0005) to SGD momentum=0.9 (lr=0.002). This single change accounts for -0.041 BPB. SGD provides more aggressive parameter updates that better exploit the short adaptation window.
3-Seed Results
Ablation
Run