Prob Output none seeded Fork le
OracleComp.probOutput_none_seededFork_le
Project documentation
Main forking lemma: the failure probability is bounded by 1 - acc * (acc / q - 1/h).
Exact Lean statement
theorem probOutput_none_seededFork_le :
let acc : ℝ≥0∞Formal artifact
Lean source
theorem probOutput_none_seededFork_le : let acc : ℝ≥0∞ := ∑ s, Pr[= some s | cf <$> main] let h : ℝ≥0∞ := Fintype.card (spec.Range i) let q := qb i + 1 Pr[= none | seededFork main qb js i cf] ≤ 1 - acc * (acc / q - h⁻¹) := by simp only set ps : Fin (qb i + 1) → ℝ≥0∞ := fun s => Pr[= (some s : Option _) | cf <$> main] set acc := ∑ s, ps s set h : ℝ≥0∞ := ↑(Fintype.card (spec.Range i)) have htotal := probOutput_none_add_tsum_some (mx := seededFork main qb js i cf) rw [probFailure_of_liftM_PMF, tsub_zero] at htotal calc Pr[= none | seededFork main qb js i cf] _ = 1 - ∑' p, Pr[= some p | seededFork main qb js i cf] := ENNReal.eq_sub_of_add_eq (ne_top_of_le_ne_top one_ne_top (htotal ▸ le_add_self)) htotal _ ≤ 1 - ∑ s, Pr[ fun r => r.map (cf ∘ Prod.fst) = some (some s) | seededFork main qb js i cf] := tsub_le_tsub_left (sum_probEvent_fork_le_tsum_some main qb js i cf) 1 _ ≤ 1 - ∑ s, (ps s ^ 2 - ps s / h) := tsub_le_tsub_left (Finset.sum_le_sum fun s _ => le_probOutput_seededFork main qb js i cf s) 1 _ ≤ 1 - acc * (acc / ↑(qb i + 1) - h⁻¹) := by refine tsub_le_tsub_left ?_ 1 have hsum : (∑ s, ps s) ≠ ⊤ := ne_top_of_le_ne_top one_ne_top (sum_probOutput_some_le_one (mx := cf <$> main) (α := Fin (qb i + 1))) simpa [Finset.card_univ, Fintype.card_fin] using ENNReal.mul_tsub_inv_le_sum_sq_sub_div (Finset.univ : Finset (Fin (qb i + 1))) ps h hsum- Project
- VCVio
- License
- Apache-2.0
- Commit
- 2ceb2d825ee3
- Source
- VCVio/CryptoFoundations/SeededFork.lean:605-632
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