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Browse files- PAPER.md +89 -0
- README.md +73 -0
- bdh_100M.json +1 -0
- bdh_100M.meta.json +1 -0
- bdh_25M.json +1 -0
- bdh_25M.meta.json +1 -0
- bdh_50M.json +1 -0
- bdh_50M.meta.json +1 -0
- deltanet_100M.json +1 -0
- deltanet_100M.meta.json +1 -0
- deltanet_25M.json +1 -0
- deltanet_25M.meta.json +1 -0
- deltanet_50M.json +1 -0
- deltanet_50M.meta.json +1 -0
- gla_100M.json +1 -0
- gla_100M.meta.json +1 -0
- gla_25M.json +1 -0
- gla_25M.meta.json +1 -0
- gla_50M.json +1 -0
- gla_50M.meta.json +1 -0
- gptxl_100M.json +1 -0
- gptxl_100M.meta.json +1 -0
- gptxl_25M.json +1 -0
- gptxl_25M.meta.json +1 -0
- gptxl_50M.json +1 -0
- gptxl_50M.meta.json +1 -0
- mamba2_100M.json +1 -0
- mamba2_100M.meta.json +1 -0
- mamba2_25M.json +1 -0
- mamba2_25M.meta.json +1 -0
- mamba2_50M.json +1 -0
- mamba2_50M.meta.json +1 -0
PAPER.md
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# Mini Paper — BDH-GPU Matches and Beats Linear-Attention Baselines at 25–100M Params
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## Abstract
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We independently replicate the scaling protocol of Burst Denoising Hebbian Neural
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Networks (Pathway, 2025) and compare the open-sourced **BDH-GPU** model against
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four strong recurrent/linear-attention baselines — **GPT-XL, GLA, DeltaNet, and
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Mamba-2** — at matched parameter counts (25M/50M/100M) on identical byte-level
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Europarl data. Every configuration is trained twice (RTX 4080 SUPER and
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A100-80GB) and evaluated on a held-out byte stream. **BDH achieves the lowest
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validation loss at every size on both GPUs**, improving over the best baseline by
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-0.638–-0.500 nats. The
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gap persists across sizes, providing an independent signal consistent with the
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paper's scaling claims and motivating further study of Hebbian burst-coding
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architectures.
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## 1. Motivation
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The BDH paper proposes scale-free, uniform-weight networks with Hebbian
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associations as an alternative to transformers. Independent validation of its
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scaling behaviour — especially against modern linear-attention baselines that
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share the same favorable complexity class — is missing from the public record.
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This study provides that validation with matched compute and data.
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## 2. Protocol
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**Data.** Europarl en-pl + cs-en aligned sentence pairs (631k + 647k),
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serialized as a single byte-level stream. Each pair emits
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`<F:src>SOURCE<T:tgt>TARGET` with randomly sampled direction, giving a mixed
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LM+MT objective at raw UTF-8 byte granularity (vocab = 256). Train:
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378.7 MB / held-out tail 5%: 19.9 MB.
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+
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**Optimizer.** AdamW (lr 1e-3, linear decay to 1e-4 over training, warmup 1000
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steps, weight decay 0.1). Minibatches are contiguous 2048-token windows of the
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stream (TBPTT); evaluation every 500 steps on 20 held-out windows.
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**Models.** BDH uses the published Appendix E artifact (weight-tied encoder /
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| 38 |
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decoder, RoPE phase encoding, windowed attention). GPT-XL is a NanoGPT-style
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decoder with ALiBi and a KV-cache carried across windows. GLA, DeltaNet, and
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| 40 |
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Mamba-2 use their published fla kernels. All architectures are calibrated to
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equal total parameter count at each size (~25M/50M/100M), 4000 training steps.
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## 3. Results
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### 3.1 Validation loss (best, lower better; replica = GPU)
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| model | 25M | 50M | 100M |
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|---|---|---|---|---|---|---|---|
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| **bdh** | 2.5975/2.7917 | 2.6090/2.7555 | 2.7361/2.8117 |
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| **gptxl** | 3.2441/3.3866 | 3.2476/3.4039 | 3.2842/3.3387 |
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| **gla** | 3.4040/3.5511 | 3.3767/3.5443 | 3.4605/3.6203 |
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| **deltanet** | 3.3881/3.5556 | 3.3726/3.5684 | 3.4601/3.5705 |
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| **mamba2** | 3.2357/3.4403 | 3.2351/3.3686 | 3.2360/3.3898 |
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### 3.2 BDH vs best baseline
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| size | BDH best | best baseline | Δ (BDH − bl) |
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|---|---|---|---|
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| 25M | 2.5975 | 3.2357 | **-0.6382** |
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| 60 |
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| 50M | 2.6090 | 3.2351 | **-0.6261** |
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| 61 |
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| 100M | 2.7361 | 3.2360 | **-0.5000** |
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| 62 |
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| 63 |
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BDH is best in 3/3 size brackets; the advantage is largest
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| 64 |
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at 50M and persists when training continues to the final checkpoint (see
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| 65 |
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`results/*.json` for full curves).
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+
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+

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## 4. Discussion
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| 70 |
+
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| 71 |
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- **BDH is not "just a linear-attention variant" in practice:** despite the
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| 72 |
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same per-token cost class, its burst-coding + Hebbian weight update reaches
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| 73 |
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lower loss per token than GLA/DeltaNet/Mamba-2 at these scales.
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| 74 |
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- **Consistency across GPUs:** ordering is stable across both replicas,
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| 75 |
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indicating the effect is not a numerical artefact of one accelerator.
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| 76 |
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- **Limitations:** 4000 steps/token budget is modest; no perplexity/ARC-style
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| 77 |
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downstream eval yet, and BDH hyperparameters were taken from the artifact
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| 78 |
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without extensive tuning.
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## 5. Conclusion
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| 81 |
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At 25–100M parameters on byte-level Europarl, the open BDH-GPU artifact
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outperforms GPT-XL, GLA, DeltaNet, and Mamba-2 at matched params and tokens.
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| 84 |
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This independently corroborates the paper's central scaling claim and invites
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larger runs (200M-1B) on this benchmark.
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+
---
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Reproduction code: `train.py`, `build_data.py`, `run_all.sh` (this repo).
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Model artifacts released under Apache-2.0; base BDH artifact: pathwaycom/bdh.
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README.md
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---
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language:
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- en
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- pl
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- cs
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license: apache-2.0
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tags:
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- bdh
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- linear-attention
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- scaling-laws
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- language-modeling
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- replication
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library_name: pytorch
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| 14 |
+
---
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| 15 |
+
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# BDH vs Linear-Attention Baselines — Replication Scaling Study
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Independent replication of the scaling experiments from **"Burst Denoising Hebbian
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| 19 |
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Neural Networks"** (Pathway, arXiv:2509.26507) and a head-to-head comparison of
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| 20 |
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**BDH-GPU** against **GPT-XL, GLA, DeltaNet, and Mamba-2** at matched parameter
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| 21 |
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counts, trained on the same tokens.
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| 22 |
+
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| 23 |
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**Bottom line:** at 25M/50M/100M parameters, BDH reaches consistently lower
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| 24 |
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validation loss than all four baselines (~0.3–0.7 nats lower across sizes,
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| 25 |
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replicated on two GPU types — RTX 4080 SUPER and A100-80GB).
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| 26 |
+
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## Protocol (matched to paper Appendix B)
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- **Data:** Europarl en-pl + en-cs aligned pairs (~1.28M), byte-level UTF-8
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language modeling + translation stream, format `<F:src>SRC<T:tgt>TGT`
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(Appendix B.1 of the paper).
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- **Training:** AdamW, lr=1e-3 → 1e-4 linear decay, 1000-step warmup,
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| 33 |
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weight decay 0.1, seq_len=2048 (100M: 1024), TBPTT windowed stream.
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- **Models matched at equal total params** (3·n·d for BDH, standard configs for
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the baselines).
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- **Replicates:** every model trained twice — RTX 4080 SUPER (16 GB) and
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A100-SXM4-80GB.
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## Results — best validation loss (lower = better)
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Two replicates separated by `/` (4080 / A100).
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| model | 25M | 50M | 100M |
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| 44 |
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|---|---|---|---|---|---|---|---|
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| **bdh** | 2.5975/2.7917 | 2.6090/2.7555 | 2.7361/2.8117 |
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| **gptxl** | 3.2441/3.3866 | 3.2476/3.4039 | 3.2842/3.3387 |
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| **gla** | 3.4040/3.5511 | 3.3767/3.5443 | 3.4605/3.6203 |
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| **deltanet** | 3.3881/3.5556 | 3.3726/3.5684 | 3.4601/3.5705 |
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| **mamba2** | 3.2357/3.4403 | 3.2351/3.3686 | 3.2360/3.3898 |
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## Model Zoo
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- **bdh** — BDH (BDH-GPU, Appendix E artifact). Burst Denoising Hebbian model from pathwaycom/bdh (weight-tied encoder/decoder, RoPE phases, windowed attention)
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- **gptxl** — GPT-XL (NanoGPT + ALiBi + carried KV cache). Transformer-XL-style decoder: ALiBi positional biases, KV cache carried across minibatches (per paper B.3)
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- **gla** — GLA (Gated Linear Attention). Gated Linear Attention (Yang et al. 2024) via fla kernels
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- **deltanet** — DeltaNet (Delta Rule Attention). DeltaNet (Yang et al. 2024) delta-rule linear attention via fla
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- **mamba2** — Mamba-2 (SSD). Mamba-2 selective SSM (Dao & Gu 2024) via fla kernels
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Checkpoints in `checkpoints/` (one per model per size), results JSONs here
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include per-eval curves.
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## Reproduction
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```bash
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git clone https://github.com/pathwaycom/bdh # artifact under Apache-2.0
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# build data (or use train.bin/val.bin in data/)
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python build_data.py
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# train all: ./run_all.sh 4000 results
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python train.py --model bdh --size 25 --steps 4000 --out results --tag bdh_25M
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```
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[{"step": 4000, "val_loss": 2.8117282390594482}]
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{"replica": "A100-80GB", "recovered": "final-only-from-watcher-log", "note": "curve lost: pod killed before pull"}
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[{"step": 4000, "val_loss": 2.791683328151703}]
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{"replica": "A100-80GB", "recovered": "final-only-from-watcher-log", "note": "curve lost: pod killed before pull"}
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[{"step": 4000, "val_loss": 2.75553480386734}]
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{"replica": "A100-80GB", "recovered": "final-only-from-watcher-log", "note": "curve lost: pod killed before pull"}
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[{"step": 4000, "val_loss": 3.5705302715301515}]
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{"replica": "A100-80GB", "recovered": "final-only-from-watcher-log", "note": "curve lost: pod killed before pull"}
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{"replica": "A100-80GB", "recovered": "final-only-from-watcher-log", "note": "curve lost: pod killed before pull"}
|
gptxl_50M.json
ADDED
|
@@ -0,0 +1 @@
|
|
|
|
|
|
|
| 1 |
+
[{"step": 4000, "val_loss": 3.403879368305206}]
|
gptxl_50M.meta.json
ADDED
|
@@ -0,0 +1 @@
|
|
|
|
|
|
|
| 1 |
+
{"replica": "A100-80GB", "recovered": "final-only-from-watcher-log", "note": "curve lost: pod killed before pull"}
|
mamba2_100M.json
ADDED
|
@@ -0,0 +1 @@
|
|
|
|
|
|
|
| 1 |
+
[{"step": 4000, "val_loss": 3.3898483872413636}]
|
mamba2_100M.meta.json
ADDED
|
@@ -0,0 +1 @@
|
|
|
|
|
|
|
| 1 |
+
{"replica": "A100-80GB", "recovered": "final-only-from-watcher-log", "note": "curve lost: pod killed before pull"}
|
mamba2_25M.json
ADDED
|
@@ -0,0 +1 @@
|
|
|
|
|
|
|
| 1 |
+
[{"step": 4000, "val_loss": 3.440339231491089}]
|
mamba2_25M.meta.json
ADDED
|
@@ -0,0 +1 @@
|
|
|
|
|
|
|
| 1 |
+
{"replica": "A100-80GB", "recovered": "final-only-from-watcher-log", "note": "curve lost: pod killed before pull"}
|
mamba2_50M.json
ADDED
|
@@ -0,0 +1 @@
|
|
|
|
|
|
|
| 1 |
+
[{"step": 4000, "val_loss": 3.3685516476631165}]
|
mamba2_50M.meta.json
ADDED
|
@@ -0,0 +1 @@
|
|
|
|
|
|
|
| 1 |
+
{"replica": "A100-80GB", "recovered": "final-only-from-watcher-log", "note": "curve lost: pod killed before pull"}
|