Bounding the Number of Hyperedges in Friendship $r$-Hypergraphs

Karen Gunderson, Natasha Morrison, Jason Semeraro

For $r\ge 2$, an $r$-uniform hypergraph is called a friendship $r$-hypergraph if every set $R$ of $r$ vertices has a unique 'friend' - that is, there exists a unique vertex $x \no…