theorem
LovaszLocalLemma.cond_le_of_indepSet
{Ω : Type u_1}
[MeasurableSpace Ω]
{μ : MeasureTheory.Measure Ω}
{s t : Set Ω}
(hs : MeasurableSet s)
(h : ProbabilityTheory.IndepSet t s μ)
:
For independent measurable sets $t$ and $s$, the conditional measure $\mu[t \mid s]$ is bounded above by $\mu(t)$.
theorem
LovaszLocalLemma.indepSet_of_disjoint_support
{Ω : Type u_1}
[MeasurableSpace Ω]
{μ : MeasureTheory.Measure Ω}
{N m_count : ℕ}
{β : Fin N → Type u_2}
[(j : Fin N) → MeasurableSpace (β j)]
{X : (j : Fin N) → Ω → β j}
(hX_indep : ProbabilityTheory.iIndepFun X μ)
(hX_meas : ∀ (j : Fin N), Measurable (X j))
{E : Fin m_count → Set Ω}
{B : Fin m_count → Finset (Fin N)}
(hE_dep : ∀ (i : Fin m_count), MeasurableSet (E i))
(i : Fin m_count)
(S : Finset (Fin m_count))
(h_disj : ∀ j ∈ S, Disjoint ↑(B i) ↑(B j))
:
ProbabilityTheory.IndepSet (E i) (⋂ j ∈ ↑S, (E j)ᶜ) μ
If event $E_i$ depends only on the variables indexed by $B_i$ and the sets of variables $B_i$, $B_j$ are disjoint for all $j \in S$, then $E_i$ is independent of $\bigcap_{j \in S} E_j^c$.
theorem
LovaszLocalLemma.lovasz_local_lemma_rv
{Ω : Type u_1}
[MeasurableSpace Ω]
{μ : MeasureTheory.Measure Ω}
[MeasureTheory.IsProbabilityMeasure μ]
{N m : ℕ}
{β : Fin N → Type u_2}
[(j : Fin N) → MeasurableSpace (β j)]
{X : (j : Fin N) → Ω → β j}
(hX_indep : ProbabilityTheory.iIndepFun X μ)
(hX_meas : ∀ (j : Fin N), Measurable (X j))
{E : Fin m → Set Ω}
(hE_meas : ∀ (i : Fin m), MeasurableSet (E i))
{B : Fin m → Finset (Fin N)}
(hE_dep : ∀ (i : Fin m), MeasurableSet (E i))
{d : ℕ}
{p : ℝ}
(hd : ∀ (i : Fin m), {j : Fin m | j ≠ i ∧ (B i ∩ B j).Nonempty}.card ≤ d)
(hp : ∀ (i : Fin m), (μ (E i)).toReal ≤ p)
(hLLL : Real.exp 1 * p * (↑d + 1) ≤ 1)
:
(Theorem 1.1.8, Lovász Local Lemma — random variable / mutual independence model) Let events $(E_i)_{i < m}$ each depend only on a subset $B_i$ of a family of mutually independent random variables $(X_j)_{j < N}$. If each event has probability at most $p$, each $B_i$ intersects at most $d$ other $B_j$, and $e \cdot p \cdot (d+1) \le 1$, then $\mu\bigl(\bigcap_i E_i^c\bigr) > 0$.