Function partition_of_unity 

pub fn partition_of_unity(n: usize) -> Poly

The partition of unity over the n-cube: Σ_{a ∈ {0,1}ⁿ} δ_a, the sum of every corner’s point-indicator. It is the constant 1 for all n — the identity the constructive Nullstellensatz certificate (build_ns_certificate) rests on. Computed here by direct summation (for finite checks); pou_as_product gives the closed form that proves it ∀n.