English

Computing the probability of intersection

Probability 2025-09-16 v3 Data Structures and Algorithms Combinatorics

Abstract

Let Ω1,,Ωm\Omega_1, \ldots, \Omega_m be probability spaces, let Ω=Ω1××Ωm\Omega=\Omega_1 \times \cdots \times \Omega_m be their product and let A1,,AnΩA_1, \ldots, A_n \subset \Omega be events. Suppose that each event AiA_i depends on rir_i coordinates of a point xΩx \in \Omega, x=(ξ1,,ξm)x=\left(\xi_1, \ldots, \xi_m\right), and that for each event AiA_i there are Δi\Delta_i of other events AjA_j that depend on some of the coordinates that AiA_i depends on. Let Δ=max{5, Δi:i=1,,n}\Delta=\max\{5,\ \Delta_i: i=1, \ldots, n\} and let μi=min{ri, Δi+1}\mu_i=\min\{r_i,\ \Delta_i+1\} for i=1,,ni=1, \ldots, n. We prove that if P(Ai)<(3Δ)3μiP(A_i) < (3\Delta)^{-3\mu_i} for all ii, then for any 0<ϵ<10 < \epsilon < 1, the probability P(i=1nAi)P\left( \bigcap_{i=1}^n \overline{A}_i\right) of the intersection of the complements of all AiA_i can be computed within relative error ϵ\epsilon in polynomial time from the probabilities P(Ai1Aik)P\left(A_{i_1} \cap \ldots \cap A_{i_k}\right) of kk-wise intersections of the events AiA_i for k=eO(Δ)ln(n/ϵ)k = e^{O(\Delta)} \ln (n/\epsilon).

Cite

@article{arxiv.2507.10329,
  title  = {Computing the probability of intersection},
  author = {Alexander Barvinok},
  journal= {arXiv preprint arXiv:2507.10329},
  year   = {2025}
}

Comments

22 pages, various improvements

R2 v1 2026-07-01T03:59:59.625Z