quadratic_neumann_all_distinct_inner_base_frobenius_norm_bound_min_dim
ProvedSource: Candès--Recht, Exact Matrix Completion via Convex Optimization, PDF p. 28, Section 6.2, Lemma 6.6, equations (6.15)--(6.17), and PDF p. 30, Section 6.3, equation (6.20).
Mathematical statement:
Let be rank- SVD data for satisfying and . For coordinates , let be quadraticAllDistinctInnerBaseMatrix, the all-distinct inner base matrix in the equation (6.20) branch. Then there is a universal positive constant such that
Notation context: Downstream, , is the Bernoulli rate, and is the sample set. This deterministic base-bound theorem itself does not quantify over , , or . The parameters and are the Candès--Recht incoherence parameters from and .
Formalization note:
This is a formal bridge, not a theorem stated verbatim in the paper. It composes the source-backed linear off-diagonal Frobenius base bound linear_neumann_off_diagonal_coefficient_base_frobenius_norm_bound_min_dim with the source-backed formal bridge quadratic_neumann_all_distinct_inner_base_norms_le_linear_offdiag_base, which says the all-distinct equation (6.20) base matrix is the Lemma 6.6 linear off-diagonal base matrix with one extra coordinate zeroed. This is the corrected min-dimension replacement for the disproved old max-denominator node quadratic_neumann_all_distinct_inner_base_frobenius_norm_bound.
import Definitions.Def_linear_neumann_offdiag_bernstein open MatrixCompletion open scoped Classical BigOperators
theorem quadratic_neumann_all_distinct_inner_base_frobenius_norm_bound_min_dim :
∃ Cfro : ℝ, 0 < Cfro ∧
∀ (n₁ n₂ r : ℕ) (M : Matrix (Fin n₁) (Fin n₂) ℝ)
(μ₀ μ₁ : ℝ) (S : SVD M r),
0 < n₁ → 0 < n₂ → 0 < r →
1 ≤ μ₀ → 1 ≤ μ₁ →
A0 S μ₀ → A1 S μ₁ →
∀ w1 w2 : Fin n₁ × Fin n₂,
frobeniusNorm (quadraticAllDistinctInnerBaseMatrix S w1 w2) ≤
Cfro * μ₁ *
Real.sqrt ((r : ℝ) / ((n₁ : ℝ) * (n₂ : ℝ))) *
Real.sqrt
(μ₀ * (r : ℝ) / (↑(min n₁ n₂))) := by
sorry