Article ID Journal Published Year Pages File Type
4656772 Journal of Combinatorial Theory, Series B 2015 7 Pages PDF
Abstract

Let Kp1,…,pdd denote the complete d-uniform d  -partite hypergraph with partition classes of sizes p1,…,pdp1,…,pd. A hypergraph G⊆Kn,…,nd is said to be weakly Kp1,…,pdd-saturated if one can add the edges of Kn,…,nd∖G in some order so that at each step a new copy of Kp1,…,pdd is created. Let Wn(p1,…,pd)Wn(p1,…,pd) denote the minimum number of edges in such a hypergraph. The problem of bounding Wn(p1,…,pd)Wn(p1,…,pd) was introduced by Balogh, Bollobás, Morris and Riordan who determined it when each pipi is either 1 or some fixed p  . In this note we fully determine Wn(p1,…,pd)Wn(p1,…,pd). Our proof applies a reduction to a multi-partite version of the Two Families Theorem obtained by Alon. While the reduction is combinatorial, the main idea behind it is algebraic.

Related Topics
Physical Sciences and Engineering Mathematics Discrete Mathematics and Combinatorics
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