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KYS-1.5B-Quality-Base

QUALITY-BASE โ€” the non-rewritten baseline.

1.5B-parameter Llama-2-architecture language models pretrained from scratch for the paper Know Your Sources: Data Selection Matters when Rewriting for Data-Constrained Pretraining. This repo holds all 9 checkpoints for this setting: 3 seeds ร— 3 epoch boundaries.

โš ๏ธ These are base models trained on 30B tokens. They are research artifacts for studying data selection, not instruction-tuned assistants.

What this setting does

The next 5B tokens down the DCLM fastText ranking after the shared anchor is removed from the pool, used verbatim. No rewriting anywhere in this mixture.

This is the control arm every other setting is compared against.

Every one of the six settings trains on a 10B-token mixture built the same way: a shared 5B-token anchor of top-ranked DCLM fastText documents, identical across all six settings and never rewritten, plus 5B tokens contributed by this setting's selection strategy. Only that second half differs between settings, so downstream differences isolate source selection alone.

Quick start

The repo root is a copy of seed 42 at the end of epoch 3, so from_pretrained works with no subfolder argument:

from transformers import AutoModelForCausalLM, AutoTokenizer
model = AutoModelForCausalLM.from_pretrained("blab-jhu/KYS-1.5B-Quality-Base")      # = seed42/epoch3
tok   = AutoTokenizer.from_pretrained("blab-jhu/KYS-1.5B-Quality-Base")

Any other checkpoint is addressed by subfolder:

model = AutoModelForCausalLM.from_pretrained("blab-jhu/KYS-1.5B-Quality-Base", subfolder="seed43/epoch1")

Layout

.                      <- copy of seed42/epoch3 (seed 42, end of epoch 3)
seed42/epoch1  epoch2  epoch3
seed43/epoch1  epoch2  epoch3
seed44/epoch1  epoch2  epoch3

Each directory is a complete HF checkpoint: config.json, generation_config.json, model.safetensors (bf16, 3,008,627,352 B), tokenizer.json, tokenizer_config.json, special_tokens_map.json.

Optimizer state is not included. Nanotron wrote an 18.05 GB AdamW state next to every checkpoint (fp32 master weights + both moments, 974.80 GB across the 54 released checkpoints); it is omitted from the release. These checkpoints are for inference and evaluation, not for resuming training.

Step โ†’ epoch mapping

One optimizer step consumes 4 (micro) ร— 64 (accum) ร— 4 (DP) ร— 2048 = 2,097,152 tokens.

Directory Nanotron step Tokens consumed
epoch1 4770 10,003,415,040
epoch2 9540 20,006,830,080
epoch3 14305 29,999,759,360

Checkpoints were written every 477 steps; 4770 = 477 ร— 10 and 9540 = 477 ร— 20.

Training configuration

Identical across all 18 runs (6 settings ร— 3 seeds).

Architecture Llama 2, 28 layers, hidden 2048, FFN 5632 (SwiGLU), 16 heads (MHA)
Position / norm RoPE ฮธ = 10โด, RMSNorm ฮต = 1e-5, tied embeddings
Vocabulary 32,000 (Llama 2 tokenizer)
Parameters 1,504,299,008 (1.504B; 1.439B non-embedding)
Optimizer AdamW, ฮฒ = (0.9, 0.95), ฮต = 1e-8, weight decay 0.1, grad clip 1.0
LR schedule peak 5e-4, 500-step linear warmup, WSD with linear decay to 0 over the final 10%
Batching seqlen 2048, global batch 1024 sequences = 2.10M tokens/step
Precision bf16 parameters, fp32 gradients and optimizer state
Hardware 4 ร— H100, data-parallel degree 4, ~55 h / ~220 GPU-hours per run

Seeds 42/43/44 control initialization only โ€” there is no dropout and the data order is fixed. All six settings at a given seed start from bit-identical weights, released once as KYS-Configs/nanotron/init/.

How these were produced

  1. A 100M-document pool was reservoir-sampled from DCLM-RefinedWeb and annotated with three quality scorers and a 24-way WebOrganizer topic classifier โ†’ KYS-DCLM-Refinedweb-100M-Scored.
  2. This setting's strategy selected source documents from the pool โ†’ KYS-1.5B-Pretraining-Corpora.
  3. The corpus was tokenized and trained with Nanotron; configs are in KYS-Configs.
  4. Checkpoints were converted from Nanotron to HF format with the same converter used for the paper's own evaluations. The conversion was verified by re-running LightEval on a converted checkpoint and reproducing the paper's stored numbers exactly (rw_piqa acc_norm 0.710555, rw_hellaswag acc_norm 0.486158, delta 0.000e+00).

Evaluation

LightEval, 0-shot, acc_norm with continuation-token-length-normalized log-likelihood, on ARC-Easy, HellaSwag, PIQA, SIQA, OpenBookQA, CommonsenseQA and MMLU (57 subsets). Task definitions, launchers and all 276 raw result JSONs are in KYS-Configs/eval/.

The rest of the release

Repo What it holds
KYS-1.5B-Quality-Base QUALITY-BASE โ€” non-rewritten baseline
KYS-1.5B-Quality-First QUALITY-FIRST
KYS-1.5B-Diversity-Oriented DIVERSITY-ORIENTED
KYS-1.5B-Disagreement-Aware DISAGREEMENT-AWARE (ฮป = 0.5)
KYS-1.5B-Wrap-Inspired WRAP-INSPIRED
KYS-1.5B-Rewire-Inspired REWIRE-INSPIRED
KYS-Modernbert-Quality-Scorer the distilled ModernBERT ridge quality scorer
KYS-DCLM-Refinedweb-100M-Scored the 100M-document candidate pool with all scores
KYS-Claude-Haiku-50K-Labeled the Claude Haiku annotations behind the scorer
KYS-1.5B-Pretraining-Corpora the shared anchor + six strategy remainders
KYS-Configs prompts, vLLM, Nanotron and eval configs + shared init weights

Citation

@misc{kys2026,
  title  = {Know Your Sources: Data Selection Matters when Rewriting for Data-Constrained Pretraining},
  author = {TODO},
  year   = {2026},
  note   = {TODO: fill in venue / arXiv id / URL}
}
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