E13b/c: harden real-weight speciation — full symmetry group + emergent-divergence null

E13c (the symmetry defense): alignment now runs modulo the FULL
function-preserving unit symmetry group of a ReLU MLP (per-unit positive
rescaling via canonicalise_scale, composed with Re-Basin permutations;
sanity gate recovers a permuted-and-rescaled copy exactly). Verdict: the
full group removes the independent-init barrier (residual 0.001) and
essentially none of the conflict barrier (0.502 -> 0.497) — the residual
is functional, not a missed symmetry (answers arXiv:2606.23607). The
cliff gains a hybrid-fitness readout: merged accuracy 0.97 -> 0.03 with
conflict. Floor proposition drafted (paper/si-notes.md S1): endpoint
invariance + max(eps_A, eps_B) >= mu(S)/2 for any merged model under any
alignment group.

E13b (emergent divergence): pre-registered second reading — with NO
conflicting training signal (disjoint class specialists; rolled-input
conventions), residual is 0.000 at every divergence to t_div=3200, and
the merge RESCUES the forgetting specialists (parents 0.535/0.474 ->
merged 0.955; a sustained Fisher-Muller rescue at zero barrier).
Speciation in real weights requires functional conflict; it does not
emerge from compatible specialisation on shared ancestry. LLM-scale
over-specialisation (cf. 2607.11997) deferred to Phase-3 llm_speciation.

3-panel figure, READMEs, +2 tests (149 green), make mnist wired.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BkRLcc18rwT2Lysu6PbG7v

results/speciation_real_emergent/README.md

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+# E13b — Emergent divergence (no imposed conflict): does model speciation arise spontaneously?
+
+Companion to `results/speciation_real/` (full legend and interpretation there; figure panel C of
+`speciation_real.png`). Pre-registered design: `shared` control, `disjoint` (complementary class
+specialists 0–4 vs 5–9), `augment` (same labels, inputs rolled ±3 px) — **no conflicting training
+signal anywhere** — swept over post-fork divergence `t_div ∈ [100, 3200]`, 4 replicates, with
+alignment modulo the full ReLU unit symmetry group (E13c).
+
+**Outcome (the pre-registered second reading):** residual barrier **0.000 at every divergence in both
+emergent conditions**; the merged model **rescues** the two forgetting `disjoint` specialists
+(parents → 0.535/0.474; merge ≈ 0.955 throughout — a sustained Fisher–Muller rescue at zero barrier).
+**Speciation requires functional conflict; it does not emerge from compatible specialisation on shared
+ancestry in this regime.** An honest bound on the biological analogy, and a positive design result:
+merging complementary specialists of shared ancestry is safe — the danger is conflicting conventions,
+not specialisation. LLM-scale over-specialisation is the open tier (`llm_speciation`, PNAS work order
+Phase 3).

results/speciation_real_emergent/manifest.json

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+{
+  "experiment": "speciation_real_emergent",
+  "master_seed": 813,
+  "git_commit": "f5f68f52498402ba7cc6a5193e5e357be6357446",
+  "python": "3.14.7",
+  "libraries": {
+    "numpy": "2.5.0",
+    "scipy": "1.18.0",
+    "pandas": "3.0.3",
+    "pyarrow": "24.0.0",
+    "torch": "2.12.1",
+    "torchvision": "0.27.1"
+  },
+  "rows": 72,
+  "results_sha256": "95c626e0d1854690b0ad6ceaf696caa1cff005104a0814cc044c0b6b2604482b",
+  "layer": "1.5",
+  "tier": "speciation_real"
+}

results/speciation_real_emergent/resolved_config.yaml

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+experiment: speciation_real_emergent
+seed: 813
+n_replicates: 4
+source_config:
+  experiment: speciation_real_emergent
+  kind: speciation_real
+  seed: 813
+  n_replicates: 4
+  speciation_real:
+    sizes:
+    - 784
+    - 512
+    - 512
+    - 10
+    conditions:
+    - shared
+    - disjoint
+    - augment
+    t_div:
+    - 100
+    - 200
+    - 400
+    - 800
+    - 1600
+    - 3200
+    base_steps: 500
+    lr: 0.05
+    batch: 128
+    n_eval: 2000
+    data_root: data
+  output:
+    dir: results/speciation_real_emergent