Boys-and-girls birthdays and Hadamard products

Olivier Bodini (1) , Danièle Gardy (2) , Olivier Roussel (1)

1 APR - Algorithmes, Programmes et Résolution
2 PRISM - Parallélisme, Réseaux, Systèmes, Modélisation

Boltzmann models from statistical physics, combined with methods from analytic combinatorics, give rise to efficient and easy-to-write algorithms for the random generation of combinatorial objects. This paper proposes to extend Boltzmann generators to a new field of applications by uniformly sampling a Hadamard product. Under an abstract real-arithmetic computation model, our algorithm achieves approximate-size sampling in expected time ${\cal O}$(n${\sqrt n}$) or ${\cal O}$(nσ) depending on the objects considered, with σ the standard deviation of smallest order for the component object sizes. This makes it possible to generate random objects of large size on a standard computer. The analysis heavily relies on a variant of the so-called birthday paradox, which can be modelled as an occupancy urn problem.

Domaines: Algorithme et structure de données [cs.DS]

Olivier Bodini, Danièle Gardy, Olivier Roussel. Boys-and-girls birthdays and Hadamard products. 7th International Conference on Lattice Path Combinatorics and Applications, Jul 2010, Siena, Italy. pp.85-101, ⟨10.3233/FI-2012-689⟩. ⟨hal-00641077⟩