For fixed integers , and , let denote the maximum number of edges in an -vertex -uniform hypergraph in which the union of arbitrary distinct edges contains at least vertices. In 1973, Brown, Erdős and Sós initiated the study of the function and they proved that . …
Consider the following hat guessing game: players are placed on vertices of a graph, each wearing a hat whose color is arbitrarily chosen from a set of possible colors. Each player can see the hat colors of his neighbors, but not his own hat color. All of the players are asked to …