Nat Weighted Degree coeffs To Poly le
GuruswamiSudan.natWeightedDegree_coeffsToPoly_le
Plain-language statement
The weighted degree of the polynomial constructed from coefficients is bounded by D.
Exact Lean statement
lemma natWeightedDegree_coeffsToPoly_le (k D : ℕ) (c : (weigthBoundIndices k D) → F) :
natWeightedDegree (coeffsToPoly k D c) 1 (k - 1) ≤ DFormal artifact
Lean source
lemma natWeightedDegree_coeffsToPoly_le (k D : ℕ) (c : (weigthBoundIndices k D) → F) : natWeightedDegree (coeffsToPoly k D c) 1 (k - 1) ≤ D := by have h_comb : ∃ (s : Finset (ℕ × ℕ)) (f : ℕ × ℕ → F), (coeffsToPoly k D c) = ∑ p ∈ s, f p • (monomial (F := F) p.1 p.2) ∧ ∀ p ∈ s, p.1 + (k - 1) * p.2 ≤ D := by norm_num +zetaDelta at * refine ⟨univ.image (fun p : { x // x ∈ weigthBoundIndices k D } ↦ (p.val.1, p.val.2)) , ?_, ?_ ⟩; · use fun p ↦ if h : p ∈ univ.image (fun p : { x // x ∈ weigthBoundIndices k D } ↦ (p.val.1, p.val.2)) then c ⟨p, by aesop⟩ else 0 unfold coeffsToPoly simp only [LinearMap.coe_comp, LinearEquiv.coe_coe, Function.comp_apply, linearCombination_apply, zero_smul, implies_true, sum_fintype, univ_eq_attach, Prod.mk.eta, attach_image_val, dite_smul] refine sum_bij (fun x hx ↦ x) ?_ ?_ ?_ ?_ <;> aesop · unfold weigthBoundIndices at *; aesop obtain ⟨s, f, h₁, h₂⟩ := h_comb rw [h₁] refine le_trans (natWeightedDegree_sum_le s _ _ _) ?_ refine Finset.sup_le fun p hp ↦ le_trans (natWeightedDegree_smul_le _ _ _ _) ?_ rw [natWeightedDegree_monomial_eq] aesop- Project
- ArkLib
- License
- Apache-2.0
- Commit
- fad5cbf80877
- Source
- ArkLib/Data/CodingTheory/GuruswamiSudan/Basic.lean:526-547
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Project documentation
This lemma proves the final algebraic step in the DG25 Theorem 3.1 proof. It shows that if R > e + 1, then e * (R / (R - 1)) < e + 1. The intuition is that the fraction R / (R - 1) is always greater than 1, but as R gets larger, it gets closer to 1. The hypothesis R > e + 1 provides a strong enough bound to ensure the product e * (fraction) do...
Source project: ArkLib
Person-level attribution pending.
Gadget Decompose coeff
ArkLib.Lattices.Ajtai.gadgetDecompose_coeff
Plain-language statement
The k-th coefficient (k < deg φ) of a gadget-decomposition block is exactly the corresponding digit of the corresponding input coefficient.
Source project: ArkLib
Person-level attribution pending.
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ArkLib.Lattices.Ajtai.gadgetDecompose_lawful
Plain-language statement
The base-b gadget decomposition is a lawful gadget decomposition.
Source project: ArkLib
Person-level attribution pending.