docs/LIGN_ABLATION.md

L_ign ablation — shared atom_r / persistence OFF on ℓ(α_bar)

English. Numbers only. No fluency claim. Generated 2026-09-17 19:22 PDT.

What changed

Flag --field-ignorance-ablate-shared (default off; ON for this run).

When computing ℓ(α_bar) for L_ign, the surface call uses alpha=α_bar but atom_r=None and persistent_state=None (zeros inside field_features). ℓ(α) keeps the live shared state from the train forward. Same surface head. Train α-bank unchanged (adjacent ticks).

Setup

Item	Value
resume	checkpoints/atom_native_lign_smoke/atom_native_src.pt @ 2102500
out	checkpoints/atom_native_lign_ablate/atom_native.pt @ 2105000
steps	2500
L_ign	w=0.08, m=0.85, ablate=ON, prompt-bank=OFF
also	field-loss 0.08, contrast 0.45 / margin 0.45, merge ON, slow_every 4
elapsed	44.8s (~55.7 tps)

Artifacts: docs/artifacts/lign_ablate_2k5/.

Probe (inter-prompt off-diag mean cosine)

	before	after
surface logits	0.992294	0.991780
α (field)	0.720524	0.698509

Train (selected)

See docs/artifacts/lign_ablate_2k5/train_log_excerpt.txt.

• ign: early ~0.146 then sticks at 0.150 ⇒ cos_ign≈1.0 (same hinge saturation as baseline).
• mph: 0.500; merges: 0.

Verdict vs baseline logits ~0.991

Fail — logits after 0.991780 (Δ vs before ≈ -0.0005; vs baseline after 0.991285 ≈ flat). α not killed (0.698509). Ablating shared non-α inputs on the bar call alone did not break the shared logit template.