Orientability Thresholds for Random Hypergraphs

Abstract

Leth>w> 0 be two fixed integers. LetHbe a random hypergraph whose hyperedges are all of cardinalityh. Tow-orienta hyperedge, we assign exactlywof its vertices positive signs with respect to the hyperedge, and the rest negative signs. A (w,k)-orientation ofHconsists of aw-orientation of all hyperedges ofH, such that each vertex receives at mostkpositive signs from its incident hyperedges. Whenkis large enough, we determine the threshold of the existence of a (w,k)-orientation of a random hypergraph. The (w,k)-orientation of hypergraphs is strongly related to a general version of the off-line load balancing problem. The graph case, whenh= 2 andw= 1, was solved recently by Cain, Sanders and Wormald and independently by Fernholz and Ramachandran. This settled a conjecture of Karp and Saks.