Giorgio Gilestro
01d87e504f
The real-weight image of E12, and the answer to the mode-connectivity reviewer. Small no-BN MLPs on MNIST, forked from a shared base and trained independently, are weight-averaged; we measure the linear-mode-connectivity barrier before and after in-house deterministic Git Re-Basin permutation alignment (neural/rebasin.py, scipy linear_sum_assignment), decomposing it into removable (coordinate artefact) and residual (reproductive isolation). kind: speciation_real. Result (3 reps): - shared (same task, shared fork): no barrier — trivially mergeable. - independent (same task, different init): naive 0.056, alignment removes 98% (residual 0.001) — the incompatibility is a coordinate artefact. - conflict (conflicting label maps): naive 0.496, alignment removes 0% (residual 0.496) — genuine reproductive isolation. Because alignment demonstrably works on the independent case, the conflict residual is real, not a failure to align. - Isolation cliff (speciation_real_cliff): residual rises 0.00->0.13->0.19->0.28-> 0.40->0.49 with the fraction of conflicting classes — the real-weight mirror of E12's cliff; residual==naive throughout (functional, not coordinate). rebasin.py sanity-gated (recovers a known permutation exactly). plot_speciation_real.py (2-panel), +4 pure-NumPy tests (142 green), README with honest positioning vs Git Re-Basin / Entezari / Frankle / Pari 2024 / Zhou 2026. Wired into make mnist (needs torchvision). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
67 lines
3.2 KiB
Python
67 lines
3.2 KiB
Python
"""E13 figure — real-weight model speciation with Git Re-Basin.
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(A) The barrier decomposition per condition: the linear-mode-connectivity error barrier between two
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merged MLPs, split into the part permutation alignment REMOVES (coordinate artefact) and the RESIDUAL it
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cannot (reproductive isolation). `shared` ≈ 0; `independent` (same task, different init) is almost all
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removable (residual ≈ 0 — same species, different basis); `conflict` (conflicting tasks) is almost all
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residual (real isolation). (B) The isolation cliff: residual barrier vs the fraction of conflicting
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classes — the real-weight image of E12's cliff, after alignment (so it is not a coordinate artefact).
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Usage: python figures/plot_speciation_real.py
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"""
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from __future__ import annotations
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import sys
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from pathlib import Path
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import matplotlib.pyplot as plt
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import numpy as np
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sys.path.insert(0, str(Path(__file__).parent))
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from _figlib import load_bundle, savefig # noqa: E402
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def main() -> None:
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dec, _ = load_bundle("results/speciation_real")
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cliff, _ = load_bundle("results/speciation_real_cliff")
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fig, axes = plt.subplots(1, 2, figsize=(13, 5))
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# Panel A: removable (coordinate artefact) vs residual (isolation), stacked, per condition.
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ax = axes[0]
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order = [c for c in ["shared", "independent", "conflict"] if c in set(dec["condition"])]
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g = dec.groupby("condition").agg(removable=("removable", "mean"),
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residual=("residual", "mean")).reindex(order)
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x = np.arange(len(order))
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ax.bar(x, g["removable"], 0.6, label="removable by alignment\n(coordinate artefact)", color="#9ecae1")
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ax.bar(x, g["residual"], 0.6, bottom=g["removable"], label="residual after alignment\n(reproductive isolation)",
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color="#d62728")
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ax.set_xticks(x); ax.set_xticklabels(order)
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ax.set(ylabel="linear-mode-connectivity error barrier",
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title="Merge barrier = coordinate artefact + residual isolation\n"
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"(same task even across inits is coordinate; conflict is real)")
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ax.legend(frameon=False, fontsize=8)
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# Panel B: the isolation cliff — residual barrier vs conflict fraction.
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ax = axes[1]
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cg = cliff.groupby("conflict_frac").agg(res_m=("residual", "mean"), res_s=("residual", "std"),
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nai_m=("barrier_naive", "mean")).reset_index()
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ax.plot(cg["conflict_frac"], cg["nai_m"], "--o", color="#999", lw=1.4, label="naive barrier")
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ax.plot(cg["conflict_frac"], cg["res_m"], "-o", color="#d62728", lw=2, label="residual (after alignment)")
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ax.fill_between(cg["conflict_frac"], cg["res_m"] - cg["res_s"], cg["res_m"] + cg["res_s"],
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color="#d62728", alpha=0.15)
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ax.set(xlabel="fraction of classes with conflicting labels", ylabel="error barrier",
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ylim=(-0.02, None),
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title="The reproductive-isolation cliff, in real weights\n"
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"(residual rises with task conflict — not removable by alignment)")
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ax.legend(frameon=False, fontsize=9)
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fig.suptitle("E13 — real-weight model speciation: what permutation alignment can and cannot merge",
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y=1.02, fontsize=13)
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fig.tight_layout()
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savefig(fig, "results/speciation_real", "speciation_real")
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if __name__ == "__main__":
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main()
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