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Project-declaredLean 4.31.0 · mathlib@fabf563a7c95

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) ≤ D

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma natWeightedDegree_coeffsToPoly_le (k D : ) (c : (weigthBoundIndices k D)  F) :    natWeightedDegree (coeffsToPoly k D c) 1 (k - 1)  D := by  have h_comb :  (s : Finset ( × )) (f :  ×   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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Plain-language statement

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Person-level attribution pending.

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Project-declaredLean 4.31.0

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Plain-language statement

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