Generalised round consistency completeness
RoundConsistency.generalised_round_consistency_completeness
Plain-language statement
Completeness of the round consistency check. Given a polynomial f, challenge γ, and n-th roots of unity ω, when f is honestly evaluated at the scaled points {ω i * s₀}, the round consistency check succeeds with the value (foldNth n f γ).eval (s₀^n). This establishes that the Lagrange interpolant through the evaluation points matches the n-wa...
Exact Lean statement
lemma generalised_round_consistency_completeness
{𝔽 : Type} [inst1 : Field 𝔽] [DecidableEq 𝔽] {f : Polynomial 𝔽}
{n : ℕ} [inst : NeZero n]
{γ : 𝔽}
{s₀ : 𝔽}
{ω : Fin n ↪ 𝔽}
(h : ∀ i, (ω i) ^ n = 1)
(h₁ : s₀ ≠ 0)
:
roundConsistencyCheck
γ
(fun i => (ω i * s₀, f.eval (ω i * s₀)))
((FoldingPolynomial.polyFold f n γ).eval (s₀ ^ n)) = trueFormal artifact
Lean source
lemma generalised_round_consistency_completeness {𝔽 : Type} [inst1 : Field 𝔽] [DecidableEq 𝔽] {f : Polynomial 𝔽} {n : ℕ} [inst : NeZero n] {γ : 𝔽} {s₀ : 𝔽} {ω : Fin n ↪ 𝔽} (h : ∀ i, (ω i) ^ n = 1) (h₁ : s₀ ≠ 0) : roundConsistencyCheck γ (fun i => (ω i * s₀, f.eval (ω i * s₀))) ((FoldingPolynomial.polyFold f n γ).eval (s₀ ^ n)) = true := by unfold roundConsistencyCheck simp only [beq_iff_eq] rw [CompPoly.CPolynomial.eval_toPoly, CompPoly.CPolynomial.CLagrange.cinterpolate_eq_interpolate] have eval_eval₂_pow_eq_eval_pow {s : 𝔽} (i) : eval s (eval₂ C (X ^ n) (splitNth f n i)) = (splitNth f n i).eval (s ^ n) := by rw [eval₂_eq_sum] unfold Polynomial.eval rw [Polynomial.eval₂_sum, eval₂_eq_sum] congr ext e a rw [←eval] simp simp only [polyFold_eq_sum_of_splitNth, map_pow] rw [eval_finset_sum] conv => rhs rhs ext i rw [eval_mul] simp apply Eq.trans (b := eval γ <| ∑ i : Fin n, X ^ (↑i : ℕ) * C (eval (s₀ ^ n) (f.splitNth n i))) · rw [Lagrange.eq_interpolate (ι := Fin n) (v := fun i => ω i * s₀) (s := Finset.univ) (f := (∑ i : Fin n, X ^ (↑i : ℕ) * C (eval (s₀ ^ n) (f.splitNth n i)))) (by { simp only [Finset.coe_univ, Set.injOn_univ] intro x y hxy simp at hxy tauto }) (by { simp only [X_pow_mul_C, Finset.card_univ, Fintype.card_fin] apply lt_of_le_of_lt · apply Polynomial.degree_sum_le · simp only [WithBot.bot_lt_natCast, Finset.sup_lt_iff] intro b _ simp only [degree_mul, degree_pow, degree_X, nsmul_eq_mul, mul_one] by_cases heq: eval (s₀ ^ n) (f.splitNth n b) = 0 · rw [heq,] simp · rw [degree_C] · simp only [zero_add, Nat.cast_lt, Fin.is_lt] · tauto })] congr ext i conv => lhs rw [splitNth_def n f] rw [eval_finset_sum, eval_finset_sum] conv => lhs rhs ext j rw [eval_mul, eval_eval₂_pow_eq_eval_pow] simp conv => rhs rhs ext j rw [eval_mul] simp rw [←one_mul (s₀ ^ n), ←h i] rw [mul_pow] · rw [eval_finset_sum] conv => lhs rhs ext i rw [eval_mul] simp- Project
- ArkLib
- License
- Apache-2.0
- Commit
- fad5cbf80877
- Source
- ArkLib/ProofSystem/Fri/RoundConsistency.lean:42-126
Reuse this declaration
Bring the exact result into your workflow
The import identifies the source module. Your project still needs the pinned package dependency shown on this page.
What this badge means
This completion status comes from the project or community source. It has not yet been represented here as an independent rebuild and axiom audit.
Continue in this project
Related declarations
Affine gaps lifted to interleaved codes
affine_gaps_lifted_to_interleaved_codes
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.