Nat Weighted Degree add le
GuruswamiSudan.natWeightedDegree_add_le
Plain-language statement
The weighted degree of a sum is at most the maximum of the weighted degrees.
Exact Lean statement
lemma natWeightedDegree_add_le (p q : F[X][Y]) (u v : ℕ) :
natWeightedDegree (p + q) u v ≤ max (natWeightedDegree p u v) (natWeightedDegree q u v)Formal artifact
Lean source
lemma natWeightedDegree_add_le (p q : F[X][Y]) (u v : ℕ) : natWeightedDegree (p + q) u v ≤ max (natWeightedDegree p u v) (natWeightedDegree q u v) := by refine Finset.sup_le fun m hm ↦ ?_ by_cases h : m ∈ p.support <;> by_cases h' : m ∈ q.support <;> simp_all only [Polynomial.mem_support_iff, coeff_add, ne_eq, le_sup_iff] · have h_deg : (p.coeff m + q.coeff m).natDegree ≤ max ((p.coeff m).natDegree) ((q.coeff m).natDegree) := natDegree_add_le (p.coeff m) (q.coeff m) cases max_cases (natDegree (p.coeff m)) (natDegree (q.coeff m)) <;> simp_all only [sup_of_le_left, sup_eq_left, and_self, natWeightedDegree] · exact Or.inl (le_trans (add_le_add (mul_le_mul_of_nonneg_left h_deg <| Nat.zero_le _) le_rfl) <| Finset.le_sup (f := fun m ↦ u * natDegree (p.coeff m) + v * m) <| by aesop) · exact Or.inr (le_trans (add_le_add (mul_le_mul_of_nonneg_left h_deg <| Nat.zero_le _) le_rfl) <| Finset.le_sup (f := fun m ↦ u * natDegree (q.coeff m) + v * m) <| by aesop) all_goals simp_all only [not_not, add_zero, zero_add, not_false_eq_true] · exact Or.inl <| Finset.le_sup (f := fun m ↦ u * natDegree (p.coeff m) + v * m) <| by aesop · exact Or.inr <| Finset.le_sup (f := fun m ↦ u * natDegree (q.coeff m) + v * m) <| by aesop · simp at hm- Project
- ArkLib
- License
- Apache-2.0
- Commit
- fad5cbf80877
- Source
- ArkLib/Data/CodingTheory/GuruswamiSudan/Basic.lean:477-498
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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.
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Plain-language statement
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Source project: ArkLib
Person-level attribution pending.
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Plain-language statement
The base-b gadget decomposition is a lawful gadget decomposition.
Source project: ArkLib
Person-level attribution pending.