Giorgio Gilestro
287d2326cc
The decisive experiment from the external review. 39 LoRA parent pairs (0.5B, 3 seeds) on three axes decorrelated by construction: conflict (contradictory conventions on shared prompts, private budgets fixed), compat (same prompts, SAME convention — overlap without conflict), and duration (weight divergence, zero conflict). Six pre-merge predictors; primary outcome = merge penalty (parent potential − merged achieved). League table (Spearman vs penalty, n=39): functional measures predict (dis_raw +0.460, epi_conf +0.446, p<0.005); geometry collapses (delta_cos +0.03, delta_l2 +0.17 n.s.); gradient alignment weak (−0.35); performance ~0. The first grid's apparent geometry win (+0.60) was an overlap/volume artifact — the compat control axis (added for exactly this) exposed and killed it: same overlap and data volume, zero penalty. Honest riders in the README: confidence weighting does not beat raw disagreement as a rank predictor (pre-registered internal prediction not confirmed; it does double the conflict/compat level contrast), and |rho|~0.45 is bounded by 0.5B merge-outcome noise (7B is the firm-up). Also: micro-batched gradient accumulation (OOM fix on the shared 16GB GPU), exact r-space LoRA-delta geometry (brute-force-verified test, 151 green), systemd-run runbook lesson (tmux dies with the SSH session scope on this box). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01BkRLcc18rwT2Lysu6PbG7v
29 lines
1.3 KiB
YAML
29 lines
1.3 KiB
YAML
experiment: llm_epistasis_compat
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kind: llm_epistasis
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seed: 1
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seeds: [1, 2, 3]
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n_replicates: 1
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# The missing CONTROL axis for the decisive experiment (identified from the first grid's results,
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# 2026-08-11): in the original grid every shared-data pair was a CONFLICTED pair, so the delta-cosine
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# geometry predictor could succeed as a mere task-OVERLAP detector (overlap coincided with conflict by
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# construction). This sweep adds overlap WITHOUT conflict: both children train on the SAME ambiguous
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# prompts with the SAME convention (asc/asc), private budgets fixed, at the same fractions as the
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# conflict sweep. Pre-registered readings: if delta_cos stays high here while merge_penalty stays ~0,
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# geometry was detecting overlap, not incompatibility, and its apparent predictive power collapses
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# once compat pairs enter the pool; functional measures (epi_conf / dis_raw) should correctly stay LOW
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# here (the parents AGREE on the shared prompts). If geometry still predicts across all three axes, the
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# falsifier stands as stated in configs/llm/epistasis.yaml.
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base_model: Qwen/Qwen2.5-0.5B-Instruct
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family_a: strings
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family_b: arith
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n_train: 400
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n_test: 80
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epochs: 3
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n_probe_each: 30
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grad_k: 32
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lora: {r: 16, alpha: 32}
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compat_fracs: [0.25, 0.5, 0.75, 1.0]
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output: {dir: results/llm_epistasis_compat}
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