Replace the v0.1 `GaussianMutation` + clamp-inside-`evaluate` setup
with the canonical NSGA-II operator pair: SBX (η_c=15, per-var prob 0.5)
followed by PolynomialMutation (η_m=20, per-var prob 1/dim), composed
via `CompositeVariation`. Both are bounds-aware on their own, so the
in-evaluate clamping is dropped.
Result on ZDT1 (dim=30, pop=100, gens=1000, seed=42): mean L2 distance
to the analytical Pareto front is 0.00152 — comfortably within the
published NSGA-II range for this benchmark.
Note on the previous number: the v0.1 setup reported 0.00072 at 40k
evals, but that was an artifact of clamping inside `evaluate`. Out-of-
bounds Gaussian mutations on `x[0]` were snapping to 0, which
coincides with the ZDT1 Pareto-front extreme (f1=0). The new operator
pair has no such free lunch — it runs the actual NSGA-II algorithm —
and the new measurement is what honest convergence on ZDT1 actually
looks like.
Generations bumped from 400 to 1000 (40k → 100k evaluations) to give
the operators headroom; matches the budget DE uses for Rastrigin so
the example feels balanced.
swaits
5b1ee99a58