English

The probabilities for the number of intersections in the Buffon-Laplace needle problem in $\mathbb{R}^d$

Probability 2025-08-07 v1

Abstract

In 1974, Stoka solved Buffon's needle problem in Rd\mathbb{R}^d, d2d \ge 2, i.e. he found a closed form solution for the probability that a line segment ("needle") with length \ell intersects a grid of parallel hyperplanes with mutual distance aa\ge\ell. For the Laplace needle problem in Rd\mathbb{R}^d, where there are dd families of parallel hyperplanes with distances a1,,ada_1,\ldots,a_d fulfilling min(a1,,ad)\min(a_1,\ldots,a_d)\ge\ell, and normal vectors in the direction of the coordinate axes x1,,xdx_1,\ldots,x_d, he was only able to give a closed solution for the case that the needle intersects hyperplanes of all families simultaneously. In the present paper, we calculate the probabilities pd(i)p_d(i) of exactly ii, 0id0\le i\le d, intersection points between the needle and the hyperrectangular grid formed by the dd families, and conclude the expected value and the variance for the number of intersection points. Furthermore, we present a simulation program and some numerical results.

Keywords

Cite

@article{arxiv.2508.04640,
  title  = {The probabilities for the number of intersections in the Buffon-Laplace needle problem in $\mathbb{R}^d$},
  author = {Uwe Bäsel},
  journal= {arXiv preprint arXiv:2508.04640},
  year   = {2025}
}

Comments

12 pages, 2 figures