Mem rs code iff exists mle
ReedSolomon.mem_rs_code_iff_exists_mle
Plain-language statement
A word f belongs to the RS-code iff there exists a multilinear polynomial g such that f is evaluation of powAlgHom g on points from the eval domain.
Exact Lean statement
lemma mem_rs_code_iff_exists_mle
{f : ι → F} {deg : ℕ} :
f ∈ code domain (2 ^ deg) ↔
∃ g : F⦃≤ 1⦄[X (Fin deg)], f = evalOnPoints domain (powAlgHom g.1)Formal artifact
Lean source
lemma mem_rs_code_iff_exists_mle {f : ι → F} {deg : ℕ} : f ∈ code domain (2 ^ deg) ↔ ∃ g : F⦃≤ 1⦄[X (Fin deg)], f = evalOnPoints domain (powAlgHom g.1) := by constructor <;> intro h · rw [mem_code_iff_exists_polynomial] at h obtain ⟨g, hdeg, h⟩ := h let poly := linearMvExtension (m := deg) ⟨g, by aesop (add simp [Polynomial.mem_degreeLT]) ⟩ exists ⟨poly, by aesop (add simp [mem_restrictDegree_iff_degreeOf_le, linearMvExtension_degreeOf_lt])⟩ aesop (add simp powAlgHom_is_right_inverse_to_linearMvExtension) · obtain ⟨g, h⟩ := h exact mem_code_of_polynomial_of_natDegree_lt_of_eval (powAlgHom g.1) (lt_of_le_of_lt powAlgHom_of_restrict_degree_natDegree (by grind)) (by aesop)- Project
- ArkLib
- License
- Apache-2.0
- Commit
- fad5cbf80877
- Source
- ArkLib/Data/CodingTheory/ReedSolomon/Multilinear.lean:29-46
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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.
Gadget Decompose lawful
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.