Gadget Mul zmod vec L2Norm Sq le
ArkLib.Lattices.Ajtai.gadgetMul_zmod_vecL2NormSq_le
Plain-language statement
The J-recomposition ℓ₂² chain. From the range check ‖ẑ‖∞ ≤ γ (Eq. (20)'s ẑ ∈ S_b, symmetric model), the recomposed z = J·ẑ satisfies ‖z‖₂² ≤ zRecomposeL2SqBound γ b τ (deg φ) rows , no primitive ‖z‖₂² verifier check is needed.
Exact Lean statement
theorem gadgetMul_zmod_vecL2NormSq_le {b rows digits : ℕ} (hd : 0 < digits)
(h1 : 1 ≤ Φ.φ.natDegree) {γ : ℕ} (v : PolyVec (Rq Φ) (rows * digits))
(hv : vecLInftyNorm Φ v ≤ γ) :
‖gadgetMul Φ (b : ZMod q) v‖₂²
≤ zRecomposeL2SqBound γ b digits Φ.φ.natDegree rowsFormal artifact
Lean source
theorem gadgetMul_zmod_vecL2NormSq_le {b rows digits : ℕ} (hd : 0 < digits) (h1 : 1 ≤ Φ.φ.natDegree) {γ : ℕ} (v : PolyVec (Rq Φ) (rows * digits)) (hv : vecLInftyNorm Φ v ≤ γ) : ‖gadgetMul Φ (b : ZMod q) v‖₂² ≤ zRecomposeL2SqBound γ b digits Φ.φ.natDegree rows := by calc vecL2NormSq Φ (gadgetMul Φ (b : ZMod q) v) ≤ rows * (Φ.φ.natDegree * (vecLInftyNorm Φ (gadgetMul Φ (b : ZMod q) v)) ^ 2) := vecL2NormSq_le_card_mul_lInftyNorm_sq Φ _ _ ≤ rows * (Φ.φ.natDegree * ((∑ u ∈ Finset.range digits, b ^ u) * γ) ^ 2) := Nat.mul_le_mul_left _ (Nat.mul_le_mul_left _ (Nat.pow_le_pow_left (gadgetMul_zmod_vecLInftyNorm_le Φ hd h1 v hv) 2)) _ = zRecomposeL2SqBound γ b digits Φ.φ.natDegree rows := rfl- Project
- ArkLib
- License
- Apache-2.0
- Commit
- fad5cbf80877
- Source
- ArkLib/Commitments/Functional/Hachi/Gadget/Norms.lean:235-246
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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.
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.