Generating all sets with bounded unions

Yannick Frein (1) , Benjamin Lévêque (2) , András Sebő (2)

1 G-SCOP_GCSP - Gestion et Conduite des Systèmes de Production
2 G-SCOP_OC - Optimisation Combinatoire

We consider the problem of minimizing the size of a family of sets G such that every subset of 1,...,n can be written as a disjoint union of at most k members of G, where k and n are given numbers. This problem originates in a real-world application aiming at the diversity of industrial production. At the same time, the minimum of G so that every subset of 1,...,n is the union of two sets in G has been asked by Erdos and studied recently by Furedi and Katona without requiring the disjointness of the sets. A simple construction providing a feasible solution is conjectured to be optimal for this problem for all values of n and k and regardless of the disjointness requirement; we prove this conjecture in special cases including all (n,k) for which n <= 3k holds, and some individual values of n and k.

Mots clés: Turan type problems; extremal problems in graphs and hypergraphs; diversity; semi-finished products

Domaines: Mathématique discrète [cs.DM]

Yannick Frein, Benjamin Lévêque, András Sebő. Generating all sets with bounded unions. Combinatorics, Probability and Computing, 2008, 17, pp.641-660. ⟨10.1017/S096354830800922X⟩. ⟨hal-00189041⟩