society: multi-locus recombination frame — the vertical claim (E7/E8)

Enter the Lamarckian society with a robust theoretical frame. The single-
locus, fixed-p* model can only express recovery toward a ceiling; the
society's load-bearing claim is vertical -- capability that EXCEEDS any
component. Generalize knowledge to a distribution over genotypes (L
biallelic loci, K=2^L, additive fitness = # correct loci), reusing all the
K-mode machinery. The one new operator is recombination: free recombination
sends p -> product of per-locus marginals (linkage equilibrium).

E8 (star, kind: society) -- the vertical claim / Fisher-Muller: decorrelated
PARENTS (specialists, expert on their loci, agnostic elsewhere) are
recombined; sexual merge assembles a genotype fitter than any parent,
climbing to the optimum (12/12, a genotype no parent had) as parent count
grows and rho->0, while the best single parent (~8.7) and the mean-mixture
"model soup" (~11.6) plateau below. Reuses make_retention_matrix (locus
mastery replaces tail-item retention).

E7 (kind: genotype_lineage) -- the advantage of sex: a single population
adapts toward the optimum; the sexual lineage adapts faster than asexual
(clonal interference) by keeping loci in linkage equilibrium (LD->0 vs LD
spike). Honest scope: a speed advantage, not a permanent Muller's-ratchet
gap (subtle to force); E8 carries the headline.

Metaphor shift (per GG): the society is sexual reproduction with UNBOUNDED
parents, not teacher->pupil. Teacher->pupil caps at the ceiling; n-parent
recombination is combinatorial and generative, and unlike biology there is
no two-parent limit. Collapse = asexual degradation; the cure = sex. This
unifies E4 (merge != average) + E6 (irreversibility) under evolution-of-sex
theory and reaches ground Riis's single-locus n-grams cannot.

New: knowledge/{genotype,genotype_lineage,society}.py, configs/layer1/{E7,
E8}.yaml, figures/plot_{E7,E8}.py, READMEs, tests/test_genotype.py (+7).
experiment.py dispatch (kind in {genotype_lineage, society}); make layer1
wired. 112 tests green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

configs/layer1/E7.yaml

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+experiment: E7
+kind: genotype_lineage
+seed: 20260705
+n_replicates: 20
+
+# (The advantage of sex — the dynamic mechanism behind E8): a single population adapts from all-wrong
+# toward a multi-locus optimum under selection + drift + mutation. Beneficial alleles arise in
+# different sub-lineages; recombination reassorts them into one genotype, while an asexual lineage
+# suffers clonal interference (the alleles compete and cannot combine). Expect the SEXUAL lineage
+# (recomb_rate=1) to climb toward the optimum faster than the ASEXUAL one (recomb_rate=0) — the
+# classical advantage of sex, and the reason a lone model lineage cannot do what a recombining
+# society can. Honest scope: a SPEED advantage, not a dramatic permanent gap (the single-population
+# ratchet is subtle); E8 carries the headline. Falsifier: sexual adapts no faster than asexual.
+
+genotype:
+  L: 12
+  n: 150           # population/resample size (drift strength)
+  mu: 0.02         # per-locus mutation (flip) rate
+  base: 1.3        # multiplicative selection: fitness weight = base^(#correct loci)
+  recomb_rate: 0.0 # overwritten per arm by the sweep
+  init: wrong      # start all-wrong (load L); adapt upward
+
+generations: 120
+
+sweep:
+  - param: genotype.recomb_rate
+    values: [0.0, 1.0]     # asexual vs sexual
+
+output: {dir: results/E7}

configs/layer1/E8.yaml

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+experiment: E8
+kind: society
+seed: 20260705
+n_replicates: 40
+
+# (The vertical claim / Fisher-Muller — the society headline): can an offspring recombined from
+# MANY decorrelated parents be fitter than ANY parent? Each parent is a specialist: confident-
+# correct (hi) on the loci it has mastered, agnostic (~0.5) elsewhere; which loci each masters comes
+# from the exact shared-switch construction, so parent count K_T and decorrelation rho are clean
+# knobs. Deployed capability = fitness of the MODE genotype. Compare best single parent vs mean-
+# mixture ("model soup", combine-but-don't-recombine) vs sexual recombination (assemble the best
+# allele of each locus across all parents). Expect: sexual climbs to the optimum (=L, a genotype NO
+# parent had) as K_T grows and rho->0, while best-parent and average plateau far below. Unlike
+# biological sex there is no two-parent limit. Falsifier: sexual never exceeds the best parent, or
+# averaging matches sexual.
+
+society:
+  L: 12            # loci; the optimum (all-correct) has fitness 12 and no parent possesses it
+  q: 0.5           # fraction of loci each parent masters (marginal mastery)
+  hi: 0.9          # correct-allele prob on a mastered locus (confident expert)
+  lo: 0.45         # correct-allele prob on an unmastered locus (agnostic, slightly wrong)
+
+sweep:
+  - param: K_T
+    values: [1, 2, 3, 5, 8, 12]     # number of parents (unbounded; grows the recombinant reach)
+  - param: rho
+    values: [0.0, 0.5, 1.0]         # decorrelated -> identical parents (the control)
+
+output: {dir: results/E8}