The size of minimum 3‐trees: Cases 3 and 4 mod 6

A 3‐uniform hypergraph is called a minimum 3‐tree, if for any 3‐coloring of its vertex set there is a heterochromatic edge and the hypergraph has the minimum possible number of edges. Here we show that the number of edges in such 3‐tree is for any number of vertices n ≡ 3, 4 (mod 6). © 1999 John Wiley & Sons, Inc. J Graph Theory 30: 157‐166, 1999